diff --git a/projects/plugins/jetpack/_inc/client/newsletter/newsletter-categories.jsx b/projects/plugins/jetpack/_inc/client/newsletter/newsletter-categories.jsx
index 9eeb45c8d0723..b01c64d9bee8b 100644
--- a/projects/plugins/jetpack/_inc/client/newsletter/newsletter-categories.jsx
+++ b/projects/plugins/jetpack/_inc/client/newsletter/newsletter-categories.jsx
@@ -54,7 +54,10 @@ function NewsletterCategories( props ) {
 		dispatch,
 	} = props;
 
-	const checkedCategoriesIds = newsletterCategories.map( mapCategoriesIds );
+	const checkedCategoriesIds = useMemo(
+		() => newsletterCategories?.map( mapCategoriesIds ) ?? [],
+		[ newsletterCategories ]
+	);
 
 	const mappedCategories = useMemo(
 		() =>
diff --git a/projects/plugins/jetpack/_inc/lib/class-jetpack-newsletter-category-helper.php b/projects/plugins/jetpack/_inc/lib/class-jetpack-newsletter-category-helper.php
new file mode 100644
index 0000000000000..96488541c8c15
--- /dev/null
+++ b/projects/plugins/jetpack/_inc/lib/class-jetpack-newsletter-category-helper.php
@@ -0,0 +1,90 @@
+<?php
+/**
+ * Contains utilities related to the Jetpack Newsletter Categories.
+ *
+ * @package automattic/jetpack
+ */
+
+/**
+ * Jetpack_Newsletter_Category_Helper class
+ */
+class Jetpack_Newsletter_Category_Helper {
+
+	const NEWSLETTER_CATEGORIES_OPTION = 'wpcom_newsletter_categories';
+
+	/**
+	 * Return category ID's
+	 *
+	 * @return array An array of integers
+	 */
+	public static function get_category_ids() {
+		$newsletter_categories = maybe_unserialize( get_option( 'wpcom_newsletter_categories', array() ) );
+
+		if ( ! is_array( $newsletter_categories ) || empty( $newsletter_categories ) ) {
+			return array();
+		}
+
+		// Check if it is an array of integers.
+		// [123, 456]
+		if ( isset( $newsletter_categories[0] ) && is_int( $newsletter_categories[0] ) ) {
+			return $newsletter_categories;
+		}
+
+		// Check if it is an array of arrays with term_id keys.
+		// [{term_id: 123}, {term_id: 456}]
+		if ( isset( $newsletter_categories[0] ) && is_array( $newsletter_categories[0] ) && isset( $newsletter_categories[0]['term_id'] ) ) {
+			$ids = array();
+			foreach ( $newsletter_categories as $category ) {
+				if ( isset( $category['term_id'] ) && is_numeric( $category['term_id'] ) ) {
+					$ids[] = (int) $category['term_id'];
+				}
+			}
+			return $ids;
+		}
+
+		return array();
+	}
+
+	/**
+	 * Handles category ID's ready to be saved as an option
+	 *
+	 * @param array $newsletter_categories An array of id's that could be in a few different forms.
+	 * @return array|bool An associated array with term_id keys on success, or the boolean result from update_option.
+	 *              [{term_id: 123}, {term_id: 456}]
+	 */
+	public static function save_category_ids( $newsletter_categories ) {
+		if ( ! is_array( $newsletter_categories ) || empty( $newsletter_categories ) ) {
+			return false;
+		}
+
+		$formatted_categories = array();
+
+		// Check if it is an array of integers.
+		// [123, 456]
+		if ( isset( $newsletter_categories[0] ) && is_numeric( $newsletter_categories[0] ) ) {
+			foreach ( $newsletter_categories as $id ) {
+				if ( is_numeric( $id ) ) {
+					$formatted_categories[] = array( 'term_id' => (int) $id );
+				}
+			}
+		}
+
+		// Check if it is an array of arrays with term_id keys.
+		// [{term_id: 123}, {term_id: 456}]
+		if ( isset( $newsletter_categories[0] ) && is_array( $newsletter_categories[0] ) && isset( $newsletter_categories[0]['term_id'] ) ) {
+			foreach ( $newsletter_categories as $category ) {
+				if ( isset( $category['term_id'] ) && is_numeric( $category['term_id'] ) ) {
+					$formatted_categories[] = array( 'term_id' => (int) $category['term_id'] );
+				}
+			}
+		}
+
+		if ( empty( $formatted_categories ) ) {
+			return false;
+		}
+
+		return update_option( self::NEWSLETTER_CATEGORIES_OPTION, $formatted_categories )
+			? $formatted_categories
+			: false;
+	}
+}
diff --git a/projects/plugins/jetpack/_inc/lib/core-api/class.jetpack-core-api-module-endpoints.php b/projects/plugins/jetpack/_inc/lib/core-api/class.jetpack-core-api-module-endpoints.php
index 280b89e35fb7f..7edc3bc64aa5c 100644
--- a/projects/plugins/jetpack/_inc/lib/core-api/class.jetpack-core-api-module-endpoints.php
+++ b/projects/plugins/jetpack/_inc/lib/core-api/class.jetpack-core-api-module-endpoints.php
@@ -504,6 +504,12 @@ public function get_all_options() {
 			$response['newsletter_has_active_plan'] = count( Jetpack_Memberships::get_all_newsletter_plan_ids( false ) ) > 0;
 		}
 
+		// Make sure we are returning a consistent type
+		if ( ! class_exists( 'Jetpack_Newsletter_Category_Helper' ) ) {
+			require_once JETPACK__PLUGIN_DIR . '_inc/lib/class-jetpack-newsletter-category-helper.php';
+		}
+		$response['wpcom_newsletter_categories'] = Jetpack_Newsletter_Category_Helper::get_category_ids();
+
 		return rest_ensure_response( $response );
 	}
 
@@ -650,6 +656,10 @@ public function update_data( $request ) {
 			}
 		}
 
+		if ( ! class_exists( 'Jetpack_Newsletter_Category_Helper' ) ) {
+			require_once JETPACK__PLUGIN_DIR . '_inc/lib/class-jetpack-newsletter-category-helper.php';
+		}
+
 		foreach ( $params as $option => $value ) {
 
 			// Used if there was an error. Can be overwritten with specific error messages.
@@ -1050,43 +1060,24 @@ function ( &$value ) {
 					}
 					break;
 
-				case 'wpcom_newsletter_categories':
-					$sanitized_category_ids = (array) $value;
-
-					array_walk_recursive(
-						$sanitized_category_ids,
-						function ( &$value ) {
-							if ( is_int( $value ) && $value > 0 ) {
-								return;
-							}
-
-							$value = (int) $value;
-							if ( $value <= 0 ) {
-								$value = null;
-							}
-						}
-					);
-
-					$sanitized_category_ids = array_unique(
-						array_filter(
-							$sanitized_category_ids,
-							function ( $category_id ) {
-								return $category_id !== null;
-							}
-						)
-					);
+				case Jetpack_Newsletter_Category_Helper::NEWSLETTER_CATEGORIES_OPTION:
+					if ( ! is_array( $value ) || empty( $value ) ) {
+						break;
+					}
 
-					$new_value = array_map(
-						function ( $category_id ) {
-							return array( 'term_id' => $category_id );
-						},
-						$sanitized_category_ids
-					);
+					// If we are already current, do nothing
+					$current_value = Jetpack_Newsletter_Category_Helper::get_category_ids();
+					if ( $value === $current_value ) {
+						break;
+					}
 
-					if ( ! update_option( $option, $new_value ) ) {
+					if ( Jetpack_Newsletter_Category_Helper::save_category_ids( $value ) ) {
+						$updated = true;
+					} else {
 						$updated = false;
-						$error   = esc_html__( 'WPCOM Newsletter Categories failed to process.', 'jetpack' );
+						$error   = esc_html__( 'Newsletter category did not update.', 'jetpack' );
 					}
+
 					break;
 
 				default:
diff --git a/projects/plugins/jetpack/changelog/arcanagelinis-newsletter-fix-v2 b/projects/plugins/jetpack/changelog/arcanagelinis-newsletter-fix-v2
new file mode 100644
index 0000000000000..8248ae0157b01
--- /dev/null
+++ b/projects/plugins/jetpack/changelog/arcanagelinis-newsletter-fix-v2
@@ -0,0 +1,4 @@
+Significance: patch
+Type: bugfix
+
+Newsletter: fix bug in category settings
diff --git a/projects/plugins/jetpack/json-endpoints/class.wpcom-json-api-site-settings-endpoint.php b/projects/plugins/jetpack/json-endpoints/class.wpcom-json-api-site-settings-endpoint.php
index bf9bf97532610..f07a8eaaf3ebb 100644
--- a/projects/plugins/jetpack/json-endpoints/class.wpcom-json-api-site-settings-endpoint.php
+++ b/projects/plugins/jetpack/json-endpoints/class.wpcom-json-api-site-settings-endpoint.php
@@ -374,22 +374,11 @@ public function get_settings_response() {
 						)
 					);
 
-					$newsletter_categories   = maybe_unserialize( get_option( 'wpcom_newsletter_categories', array() ) );
-					$newsletter_category_ids = array_filter(
-						array_map(
-							function ( $newsletter_category ) {
-								if ( is_array( $newsletter_category ) && isset( $newsletter_category['term_id'] ) ) {
-									// This is the expected format.
-									return (int) $newsletter_category['term_id'];
-								} elseif ( is_numeric( $newsletter_category ) ) {
-									// This is a previous format caused by a bug.
-									return (int) $newsletter_category;
-								}
-								return null;
-							},
-							$newsletter_categories
-						)
-					);
+					// Make sure we are returning a consistent type
+					if ( ! class_exists( 'Jetpack_Newsletter_Category_Helper' ) ) {
+						require_once JETPACK__PLUGIN_DIR . '_inc/lib/class-jetpack-newsletter-category-helper.php';
+					}
+					$newsletter_category_ids = Jetpack_Newsletter_Category_Helper::get_category_ids();
 
 					$api_cache = $site->is_jetpack() ? (bool) get_option( 'jetpack_api_cache_enabled' ) : true;
 
@@ -673,6 +662,10 @@ public function update_settings() {
 		$sharing_options              = array();
 		$updated                      = array();
 
+		if ( ! class_exists( 'Jetpack_Newsletter_Category_Helper' ) ) {
+			require_once JETPACK__PLUGIN_DIR . '_inc/lib/class-jetpack-newsletter-category-helper.php';
+		}
+
 		foreach ( $input as $key => $value ) {
 
 			if ( ! is_array( $value ) ) {
@@ -1070,42 +1063,12 @@ function ( &$value ) {
 					$updated[ $key ] = (int) (bool) $value;
 					break;
 
-				case 'wpcom_newsletter_categories':
-					$sanitized_category_ids = (array) $value;
-
-					array_walk_recursive(
-						$sanitized_category_ids,
-						function ( &$value ) {
-							if ( is_int( $value ) && $value > 0 ) {
-								return;
-							}
-
-							$value = (int) $value;
-							if ( $value <= 0 ) {
-								$value = null;
-							}
-						}
-					);
-
-					$sanitized_category_ids = array_unique(
-						array_filter(
-							$sanitized_category_ids,
-							function ( $category_id ) {
-								return $category_id !== null;
-							}
-						)
-					);
-
-					$new_value = array_map(
-						function ( $category_id ) {
-							return array( 'term_id' => $category_id );
-						},
-						$sanitized_category_ids
-					);
-
-					if ( update_option( $key, $new_value ) ) {
-						$updated[ $key ] = $sanitized_category_ids;
+				case Jetpack_Newsletter_Category_Helper::NEWSLETTER_CATEGORIES_OPTION:
+					$update_newsletter_categories = Jetpack_Newsletter_Category_Helper::save_category_ids( (array) $value );
+					if ( $update_newsletter_categories ) {
+						$updated[ $key ] = $update_newsletter_categories;
 					}
+
 					break;
 
 				case 'wpcom_newsletter_categories_enabled':
diff --git a/projects/plugins/jetpack/tests/php/_inc/lib/Jetpack_Newsletter_Category_Helper_Test.php b/projects/plugins/jetpack/tests/php/_inc/lib/Jetpack_Newsletter_Category_Helper_Test.php
new file mode 100644
index 0000000000000..8e7bebe848fbd
--- /dev/null
+++ b/projects/plugins/jetpack/tests/php/_inc/lib/Jetpack_Newsletter_Category_Helper_Test.php
@@ -0,0 +1,195 @@
+<?php
+/**
+ * Newsletter Category Helper unit tests.
+ *
+ * @package automattic/jetpack
+ */
+
+use PHPUnit\Framework\Attributes\CoversClass;
+
+require_once JETPACK__PLUGIN_DIR . '/_inc/lib/class-jetpack-newsletter-category-helper.php';
+
+/**
+ * Class for testing the Jetpack_Newsletter_Category_Helper class.
+ *
+ * @covers \Jetpack_Newsletter_Category_Helper
+ */
+#[CoversClass( Jetpack_Newsletter_Category_Helper::class )]
+class Jetpack_Newsletter_Category_Helper_Test extends WP_UnitTestCase {
+	use \Automattic\Jetpack\PHPUnit\WP_UnitTestCase_Fix;
+
+	/**
+	 * Set up before each test.
+	 */
+	public function set_up() {
+		parent::set_up();
+		delete_option( 'wpcom_newsletter_categories' );
+	}
+
+	/**
+	 * Clean up after each test.
+	 */
+	public function tear_down() {
+		delete_option( 'wpcom_newsletter_categories' );
+		parent::tear_down();
+	}
+
+	/**
+	 * Test get_category_ids() returns empty array when option doesn't exist.
+	 */
+	public function test_get_category_ids_no_option() {
+		$result = Jetpack_Newsletter_Category_Helper::get_category_ids();
+		$this->assertEquals( array(), $result );
+	}
+
+	/**
+	 * Test get_category_ids() returns empty array when option is empty.
+	 */
+	public function test_get_category_ids_empty_option() {
+		update_option( 'wpcom_newsletter_categories', array() );
+		$result = Jetpack_Newsletter_Category_Helper::get_category_ids();
+		$this->assertEquals( array(), $result );
+	}
+
+	/**
+	 * Test get_category_ids() returns empty array when option is not an array.
+	 */
+	public function test_get_category_ids_invalid_option() {
+		update_option( 'wpcom_newsletter_categories', 'not-an-array' );
+		$result = Jetpack_Newsletter_Category_Helper::get_category_ids();
+		$this->assertEquals( array(), $result );
+	}
+
+	/**
+	 * Test get_category_ids() handles array of integers format.
+	 */
+	public function test_get_category_ids_integer_array() {
+		$categories = array( 123, 456, 789 );
+		update_option( 'wpcom_newsletter_categories', $categories );
+		$result = Jetpack_Newsletter_Category_Helper::get_category_ids();
+		$this->assertEquals( $categories, $result );
+	}
+
+	/**
+	 * Test get_category_ids() handles array of arrays with term_id format.
+	 */
+	public function test_get_category_ids_term_id_array() {
+		$categories = array(
+			array( 'term_id' => 123 ),
+			array( 'term_id' => 456 ),
+			array( 'term_id' => 789 ),
+		);
+		update_option( 'wpcom_newsletter_categories', $categories );
+		$result = Jetpack_Newsletter_Category_Helper::get_category_ids();
+		$this->assertEquals( array( 123, 456, 789 ), $result );
+	}
+
+	/**
+	 * Test get_category_ids() filters out non-numeric term_ids.
+	 */
+	public function test_get_category_ids_filters_invalid_term_ids() {
+		$categories = array(
+			array( 'term_id' => 123 ),
+			array( 'term_id' => 'not-a-number' ),
+			array( 'term_id' => 456 ),
+		);
+		update_option( 'wpcom_newsletter_categories', $categories );
+		$result = Jetpack_Newsletter_Category_Helper::get_category_ids();
+		$this->assertEquals( array( 123, 456 ), $result );
+	}
+
+	/**
+	 * Test get_category_ids() handles serialized data.
+	 */
+	public function test_get_category_ids_serialized_data() {
+		$categories = array( 123, 456 );
+		update_option( 'wpcom_newsletter_categories', serialize( $categories ) );
+		$result = Jetpack_Newsletter_Category_Helper::get_category_ids();
+		$this->assertEquals( $categories, $result );
+	}
+
+	/**
+	 * Test save_category_ids() returns false for empty array.
+	 */
+	public function test_save_category_ids_empty_array() {
+		$result = Jetpack_Newsletter_Category_Helper::save_category_ids( array() );
+		$this->assertFalse( $result );
+	}
+
+	/**
+	 * Test save_category_ids() formats array of integers correctly.
+	 */
+	public function test_save_category_ids_integer_array() {
+		$input    = array( 123, 456, 789 );
+		$expected = array(
+			array( 'term_id' => 123 ),
+			array( 'term_id' => 456 ),
+			array( 'term_id' => 789 ),
+		);
+		$result   = Jetpack_Newsletter_Category_Helper::save_category_ids( $input );
+		$this->assertEquals( $expected, $result );
+
+		$saved_option = get_option( 'wpcom_newsletter_categories' );
+		$this->assertEquals( $expected, $saved_option );
+	}
+
+	/**
+	 * Test save_category_ids() handles string numeric values.
+	 */
+	public function test_save_category_ids_string_numeric() {
+		$input    = array( '123', '456', '789' );
+		$expected = array(
+			array( 'term_id' => 123 ),
+			array( 'term_id' => 456 ),
+			array( 'term_id' => 789 ),
+		);
+		$result   = Jetpack_Newsletter_Category_Helper::save_category_ids( $input );
+		$this->assertEquals( $expected, $result );
+	}
+
+	/**
+	 * Test save_category_ids() filters out non-numeric values.
+	 */
+	public function test_save_category_ids_filters_non_numeric() {
+		$input    = array( 123, 'not-a-number', 456 );
+		$expected = array(
+			array( 'term_id' => 123 ),
+			array( 'term_id' => 456 ),
+		);
+		$result   = Jetpack_Newsletter_Category_Helper::save_category_ids( $input );
+		$this->assertEquals( $expected, $result );
+	}
+
+	/**
+	 * Test save_category_ids() handles array of arrays with term_id.
+	 */
+	public function test_save_category_ids_term_id_array() {
+		$input = array(
+			array( 'term_id' => 123 ),
+			array( 'term_id' => 456 ),
+			array( 'term_id' => 789 ),
+		);
+
+		$result = Jetpack_Newsletter_Category_Helper::save_category_ids( $input );
+		$this->assertEquals( $input, $result );
+	}
+
+	/**
+	 * Test save_category_ids() returns false when no valid categories.
+	 */
+	public function test_save_category_ids_no_valid_categories() {
+		$input  = array( 'not-a-number', 'also-not-a-number' );
+		$result = Jetpack_Newsletter_Category_Helper::save_category_ids( $input );
+		$this->assertFalse( $result );
+	}
+
+	/**
+	 * Test integration between save and get methods.
+	 */
+	public function test_save_and_get_integration() {
+		$input = array( 123, 456, 789 );
+		Jetpack_Newsletter_Category_Helper::save_category_ids( $input );
+		$result = Jetpack_Newsletter_Category_Helper::get_category_ids();
+		$this->assertEquals( $input, $result );
+	}
+}