diff --git a/spring-web/src/main/java/org/springframework/http/codec/ServerSentEvent.java b/spring-web/src/main/java/org/springframework/http/codec/ServerSentEvent.java
index c913a16ce82..f2af79ab2ca 100644
--- a/spring-web/src/main/java/org/springframework/http/codec/ServerSentEvent.java
+++ b/spring-web/src/main/java/org/springframework/http/codec/ServerSentEvent.java
@@ -22,7 +22,6 @@ import org.jspecify.annotations.Nullable;
 
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
-import org.springframework.util.StringUtils;
 
 /**
  * Representation for a Server-Sent Event for use with Spring's reactive Web support.
@@ -112,7 +111,9 @@ public final class ServerSentEvent<T> {
 			appendAttribute("retry", this.retry.toMillis(), sb);
 		}
 		if (this.comment != null) {
-			sb.append(':').append(StringUtils.replace(this.comment, "\n", "\n:")).append('\n');
+			sb.append(':');
+			appendEscaped(this.comment, "\n:", sb);
+			sb.append('\n');
 		}
 		if (this.data != null) {
 			sb.append("data:");
@@ -124,6 +125,30 @@ public final class ServerSentEvent<T> {
 		sb.append(fieldName).append(':').append(fieldValue).append('\n');
 	}
 
+	private void appendEscaped(String input, String replacement, StringBuilder sb) {
+		if (input.indexOf('\n') == -1 && input.indexOf('\r') == -1) {
+			sb.append(input);
+		}
+		else {
+			int length = input.length();
+			for (int i = 0; i < length; i++) {
+				char c = input.charAt(i);
+				if (c == '\r') {
+					if (i + 1 < length && input.charAt(i + 1) == '\n') {
+						i++;
+					}
+					sb.append(replacement);
+				}
+				else if (c == '\n') {
+					sb.append(replacement);
+				}
+				else {
+					sb.append(c);
+				}
+			}
+		}
+	}
+
 	@Override
 	public boolean equals(@Nullable Object other) {
 		return (this == other || (other instanceof ServerSentEvent<?> that &&
diff --git a/spring-web/src/test/java/org/springframework/http/codec/ServerSentEventTests.java b/spring-web/src/test/java/org/springframework/http/codec/ServerSentEventTests.java
index a106ea07337..9e1a1d7c76f 100644
--- a/spring-web/src/test/java/org/springframework/http/codec/ServerSentEventTests.java
+++ b/spring-web/src/test/java/org/springframework/http/codec/ServerSentEventTests.java
@@ -22,6 +22,7 @@ import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
 
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 
 /**
@@ -44,6 +45,15 @@ class ServerSentEventTests {
 				ServerSentEvent.<String>builder().event("first" + newLine + "second").build());
 	}
 
+
+	@ParameterizedTest(name = "{1}")
+	@MethodSource("newLineCharacters")
+	void supportMultiLineComments(String newLine, String description) {
+		ServerSentEvent<String> event = ServerSentEvent.<String>builder()
+				.comment("foo" + newLine + "bar" + newLine + "baz").data("payload").build();
+		assertThat(event.format()).isEqualTo(":foo\n:bar\n:baz\ndata:");
+	}
+
 	private static Stream<Arguments> newLineCharacters() {
 		return Stream.of(
 				Arguments.of("\n", "LF"),
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/SseEmitter.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/SseEmitter.java
index c302db9f830..f0bbe9cd9b4 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/SseEmitter.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/SseEmitter.java
@@ -224,7 +224,9 @@ public class SseEmitter extends ResponseBodyEmitter {
 
 		@Override
 		public SseEventBuilder comment(String comment) {
-			append(':').append(StringUtils.replace(comment, "\n", "\n:")).append('\n');
+			append(':');
+			appendEscaped(comment, "\n:");
+			append('\n');
 			return this;
 		}
 
@@ -259,6 +261,16 @@ public class SseEmitter extends ResponseBodyEmitter {
 			if (input.indexOf('\n') == -1 && input.indexOf('\r') == -1) {
 				this.dataToSend.add(new DataWithMediaType(input, mediaType));
 			}
+			else {
+				appendEscaped(input, "\ndata:");
+				saveAppendedText(mediaType);
+			}
+		}
+
+		private void appendEscaped(String input, String replacement) {
+			if (input.indexOf('\n') == -1 && input.indexOf('\r') == -1) {
+				append(input);
+			}
 			else {
 				int length = input.length();
 				for (int i = 0; i < length; i++) {
@@ -267,16 +279,15 @@ public class SseEmitter extends ResponseBodyEmitter {
 						if (i + 1 < length && input.charAt(i + 1) == '\n') {
 							i++;
 						}
-						this.sb.append("\ndata:");
+						append(replacement);
 					}
 					else if (c == '\n') {
-						this.sb.append("\ndata:");
+						append(replacement);
 					}
 					else {
-						this.sb.append(c);
+						append(c);
 					}
 				}
-				saveAppendedText(mediaType);
 			}
 		}
 
diff --git a/spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/SseEmitterTests.java b/spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/SseEmitterTests.java
index 1b4d8ecaeb9..2ff5bfebd50 100644
--- a/spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/SseEmitterTests.java
+++ b/spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/SseEmitterTests.java
@@ -168,6 +168,17 @@ class SseEmitterTests {
 				.send(event().name("first" + newLineChars + "second")));
 	}
 
+	@ParameterizedTest(name = "{1}")
+	@MethodSource("newLineCharacters")
+	void supportMultiLineComments(String newLineChars, String description) throws Exception {
+		this.emitter.send(event().comment("foo" + newLineChars + "bar" + newLineChars + "baz").data("payload"));
+		this.handler.assertSentObjectCount(3);
+		this.handler.assertObject(0, ":foo\n:bar\n:baz\ndata:", TEXT_PLAIN_UTF8);
+		this.handler.assertObject(1, "payload");
+		this.handler.assertObject(2, "\n\n", TEXT_PLAIN_UTF8);
+		this.handler.assertWriteCount(1);
+	}
+
 	private static Stream<Arguments> newLineCharacters() {
 		return Stream.of(
 				Arguments.of("\n", "LF"),