diff --git a/projects/packages/publicize/changelog/add-social-og-optimization-tests b/projects/packages/publicize/changelog/add-social-og-optimization-tests
new file mode 100644
index 0000000000000..38ac5fb04f700
--- /dev/null
+++ b/projects/packages/publicize/changelog/add-social-og-optimization-tests
@@ -0,0 +1,4 @@
+Significance: patch
+Type: security
+
+Added new tests for the OG image optimization logic
diff --git a/projects/packages/publicize/package.json b/projects/packages/publicize/package.json
index aba04dfa9f3ae..ad9052c01dabe 100644
--- a/projects/packages/publicize/package.json
+++ b/projects/packages/publicize/package.json
@@ -1,7 +1,7 @@
 {
 	"private": true,
 	"name": "@automattic/jetpack-publicize",
-	"version": "0.42.3",
+	"version": "0.42.4-alpha",
 	"description": "Publicize makes it easy to share your site’s posts on several social media networks automatically when you publish a new post.",
 	"homepage": "https://github.com/Automattic/jetpack/tree/HEAD/projects/packages/publicize/#readme",
 	"bugs": {
diff --git a/projects/packages/publicize/tests/php/test-publicize-og-optimization.php b/projects/packages/publicize/tests/php/test-publicize-og-optimization.php
new file mode 100644
index 0000000000000..cb2e033199dc6
--- /dev/null
+++ b/projects/packages/publicize/tests/php/test-publicize-og-optimization.php
@@ -0,0 +1,251 @@
+<?php // phpcs:ignore WordPress.Files.FileName.InvalidClassFileName
+/**
+ * Testing the Settings class.
+ *
+ * @package automattic/jetpack-publicize
+ */
+
+namespace Automattic\Jetpack\Publicize;
+
+use WorDBless\BaseTestCase;
+
+/**
+ * Testing the Settings class.
+ */
+class Publicize_OG_Optimization_Test extends BaseTestCase {
+
+	const TEST_TAGS = array(
+		'og:image'        => 'http://example.com/image.jpg',
+		'og:image:width'  => '100',
+		'og:image:height' => '100',
+	);
+
+	const TEST_TAGS_WITHOUT_IMAGE = array(
+		'random_tag' => 'random_value',
+	);
+
+	const TEST_TAGS_ARRAY_IMAGE = array(
+		'og:image'        => array(
+			'https://example.com/image1.jpg',
+			'https://example.com/image2.jpg',
+		),
+		'og:image:width'  => '100',
+		'og:image:height' => '100',
+	);
+
+	/**
+	 * Mocks the publicize class and sets the return value for each function in $functions to the corresponding value in $mocks
+	 *
+	 * @param array $functions The functions to mock.
+	 * @param array $mocks The return values for each function.
+	 * @return Publicize The mocked publicize class
+	 */
+	private function mock_publicize_functions( $functions, $mocks ) {
+		$publicize = $this->getMockBuilder( Publicize::class )->setMethods( $functions )->getMock();
+
+		// We set the return value for each mock in $mocks
+		foreach ( $functions as $index => $function ) {
+			$publicize->method( $function )->withAnyParameters()->willReturn( $mocks[ $index ] );
+		}
+
+		return $publicize;
+	}
+
+	/**
+	 * Test the compress_and_scale_og_image method.
+	 */
+	public function test_compress_and_scale_og_image() {
+		$publicize = $this->mock_publicize_functions( array( 'get_resized_image_url' ), array( 'https://example.com/image_compressed' ) );
+
+		// Test that the image is not compressed or scaled if it's smaller than the requested size
+		$this->assertEquals(
+			array(
+				'url'    => 'https://example.com/image_compressed',
+				'width'  => 1000,
+				'height' => 1000,
+			),
+			$publicize->compress_and_scale_og_image( 'https://example.com/image', 1000, 1000 )
+		);
+
+		// Test that the image is compressed and scaled if it's larger than the requested size - width
+		$this->assertEquals(
+			array(
+				'url'    => 'https://example.com/image_compressed',
+				'width'  => 1200,
+				'height' => 1200 * 1000 / 2000,
+			),
+			$publicize->compress_and_scale_og_image( 'https://example.com/image', 2000, 1000 )
+		);
+
+		// Test that the image is compressed and scaled if it's larger than the requested size - height
+		$this->assertEquals(
+			array(
+				'url'    => 'https://example.com/image_compressed',
+				'width'  => 1200 * 1000 / 2000,
+				'height' => 1200,
+			),
+			$publicize->compress_and_scale_og_image( 'https://example.com/image', 1000, 2000 )
+		);
+	}
+
+	/**
+	 * Test the reduce_file_size method.
+	 */
+	public function test_reduce_file_size() {
+		$publicize = $this->mock_publicize_functions( array( 'get_resized_image_url', 'get_remote_filesize' ), array( 'https://example.com/image_compressed', 3000000 ) );
+
+		// Test that we return null if we cannot reduce the image enough
+		$this->assertNull( $publicize->reduce_file_size( 'https://example.com/image', 2000, 2000, 3000000 ) );
+
+		// Test that we scale to 75% and return if it's enough
+		$publicize = $this->mock_publicize_functions( array( 'get_resized_image_url', 'get_remote_filesize' ), array( 'https://example.com/image_compressed', 1000000 ) );
+		$this->assertEquals(
+			array(
+				'url'    => 'https://example.com/image_compressed',
+				'width'  => 2000 * 0.75,
+				'height' => 2000 * 0.75,
+			),
+			$publicize->reduce_file_size( 'https://example.com/image', 2000, 2000, 3000000 )
+		);
+	}
+
+	// jetpack_social_open_graph_filter //////////////
+
+	/**
+	 * Test that the jetpack_social_open_graph_filter method will return early if there is no OG image.
+	 */
+	public function test_jetpack_social_open_graph_filter_no_og_image() {
+		$publicize = $this->mock_publicize_functions( array( 'get_social_opengraph_image' ), array( null ) );
+
+		// Testing that the tags didn't change
+		$this->assertEquals( self::TEST_TAGS_WITHOUT_IMAGE, $publicize->jetpack_social_open_graph_filter( self::TEST_TAGS_WITHOUT_IMAGE ) );
+	}
+
+	/**
+	 * Test that the jetpack_social_open_graph_filter method will return early if the image's filesize cannot be determined.
+	 */
+	public function test_jetpack_social_open_graph_filter_invalid_filesize() {
+		$publicize = $this->mock_publicize_functions( array( 'get_social_opengraph_image', 'get_remote_filesize' ), array( null, null ) );
+
+		// Testing that the tags didn't change
+		$this->assertEquals( self::TEST_TAGS, $publicize->jetpack_social_open_graph_filter( self::TEST_TAGS ) );
+	}
+
+	/**
+	 * Test that the jetpack_social_open_graph_filter method will return early if the image's filesize is small enough.
+	 */
+	public function test_jetpack_social_open_graph_filter_small_enough_filesize() {
+		$publicize = $this->mock_publicize_functions( array( 'get_social_opengraph_image', 'get_remote_filesize' ), array( null, 1000000 ) );
+
+		// Testing that the tags didn't change
+		$this->assertEquals( self::TEST_TAGS, $publicize->jetpack_social_open_graph_filter( self::TEST_TAGS ) );
+	}
+
+	/**
+	 * Test that the jetpack_social_open_graph_filter method will return early if the OG image tag is an array as with old versions of the plugin.
+	 */
+	public function test_jetpack_social_open_graph_filter_array_og_tags() {
+		$publicize = $this->mock_publicize_functions( array( 'get_social_opengraph_image', 'get_remote_filesize' ), array( null, 1000000 ) );
+
+		// Testing that the tags didn't change
+		$this->assertEquals( self::TEST_TAGS_ARRAY_IMAGE, $publicize->jetpack_social_open_graph_filter( self::TEST_TAGS_ARRAY_IMAGE ) );
+	}
+
+	/**
+	 * Test that the jetpack_social_open_graph_filter method will compress the image, and if that is enough
+	 * we won't proceed to reduce the file size.
+	 */
+	public function test_jetpack_social_open_graph_filter_compression_enough() {
+		$publicize = $this->getMockBuilder( Publicize::class )->setMethods(
+			array(
+				'get_social_opengraph_image',
+				'get_remote_filesize',
+				'compress_and_scale_og_image',
+				'reduce_file_size',
+			)
+		)
+		->getMock();
+
+		$publicize->method( 'get_social_opengraph_image' )->withAnyParameters()->willReturn( null );
+		// Mocking so compression will be enough
+		$publicize->method( 'get_remote_filesize' )
+			->withConsecutive( array( 'http://example.com/image.jpg' ), array( 'http://example.com/image_compressed.jpg' ) )
+			->willReturnOnConsecutiveCalls( 3000000, 1200 );
+		// Mocking so that the compression decreases the size enough
+		$publicize->method( 'compress_and_scale_og_image' )->withAnyParameters()->willReturn(
+			array(
+				'url'    => 'http://example.com/image_compressed.jpg',
+				'width'  => 1000,
+				'height' => 1000,
+			)
+		);
+
+		// Check that we called the compression but not the file size reduction
+		$publicize->expects( $this->never() )->method( 'reduce_file_size' );
+		$publicize->expects( $this->once() )->method( 'compress_and_scale_og_image' );
+		$publicize->expects( $this->exactly( 2 ) )->method( 'get_remote_filesize' );
+
+		// Testing that the tags changed
+		$this->assertEquals(
+			array(
+				'og:image'        => 'http://example.com/image_compressed.jpg',
+				'og:image:width'  => 1000,
+				'og:image:height' => 1000,
+			),
+			$publicize->jetpack_social_open_graph_filter( self::TEST_TAGS )
+		);
+	}
+
+	/**
+	 * Test that the jetpack_social_open_graph_filter method will compress the image, and if that is not enough
+	 * we will proceed to reduce the file size.
+	 */
+	public function test_jetpack_social_open_graph_filter_full_flow() {
+		$publicize = $this->getMockBuilder( Publicize::class )->setMethods(
+			array(
+				'get_social_opengraph_image',
+				'get_remote_filesize',
+				'compress_and_scale_og_image',
+				'reduce_file_size',
+			)
+		)
+		->getMock();
+
+		$publicize->method( 'get_social_opengraph_image' )->withAnyParameters()->willReturn( null );
+		// Mocking so compression will be enough
+		$publicize->method( 'get_remote_filesize' )
+			->withConsecutive( array( 'http://example.com/image.jpg' ), array( 'http://example.com/image_compressed.jpg' ) )
+			->willReturnOnConsecutiveCalls( 3000000, 2500000 );
+		// Mocking so that the compression decreases the size enough
+		$publicize->method( 'compress_and_scale_og_image' )->withAnyParameters()->willReturn(
+			array(
+				'url'    => 'http://example.com/image_compressed.jpg',
+				'width'  => 1000,
+				'height' => 1000,
+			)
+		);
+
+		$publicize->method( 'reduce_file_size' )->withAnyParameters()->willReturn(
+			array(
+				'url'    => 'http://example.com/image_compressed_and_scaled.jpg',
+				'width'  => 500,
+				'height' => 500,
+			)
+		);
+
+		// Check that we didn't call reduce_file_size
+		$publicize->expects( $this->once() )->method( 'reduce_file_size' );
+		$publicize->expects( $this->once() )->method( 'compress_and_scale_og_image' );
+		$publicize->expects( $this->exactly( 2 ) )->method( 'get_remote_filesize' );
+
+		// Testing that the tags changed
+		$this->assertEquals(
+			array(
+				'og:image'        => 'http://example.com/image_compressed_and_scaled.jpg',
+				'og:image:width'  => 500,
+				'og:image:height' => 500,
+			),
+			$publicize->jetpack_social_open_graph_filter( self::TEST_TAGS )
+		);
+	}
+}