diff --git a/libraries/apollo-compiler/src/main/kotlin/com/apollographql/apollo3/compiler/ReservedKeywords.kt b/libraries/apollo-compiler/src/main/kotlin/com/apollographql/apollo3/compiler/ReservedKeywords.kt
index 5b6bd748163..c58b44dcd65 100644
--- a/libraries/apollo-compiler/src/main/kotlin/com/apollographql/apollo3/compiler/ReservedKeywords.kt
+++ b/libraries/apollo-compiler/src/main/kotlin/com/apollographql/apollo3/compiler/ReservedKeywords.kt
@@ -10,6 +10,10 @@ private val JAVA_RESERVED_WORDS = arrayOf(
     "transient", "try", "true", "void", "volatile", "while"
 )
 
+private val TYPE_REGEX = "(?:type)_*".toRegex()
+private val COMPANION_REGEX = "(?:Companion)_*".toRegex()
+private val KOTLIN_ENUM_RESERVED_WORDS_REGEX = "(?:name|ordinal)_*".toRegex()
+
 fun String.escapeJavaReservedWord() = if (this in JAVA_RESERVED_WORDS) "${this}_" else this
 
 // Does nothing. KotlinPoet will add the backticks
@@ -19,21 +23,29 @@ internal fun String.escapeTypeReservedWord(): String? {
   return when {
     // type is forbidden because we use it as a companion property to hold the CompiledType
     // See https://github.com/apollographql/apollo-kotlin/issues/4293
-    "(?:type)_*".toRegex().matches(this) -> "${this}_"
+    TYPE_REGEX.matches(this) -> "${this}_"
     else -> null
   }
 }
 
+private fun String.escapeCompanionReservedWord(): String? {
+  return when {
+    // Companion is forbidden because a Companion class is generated in enum and sealed classes
+    // See https://github.com/apollographql/apollo-kotlin/issues/4557
+    COMPANION_REGEX.matches(this) -> "${this}_"
+    else -> null
+  }
+}
 
 fun String.escapeKotlinReservedWordInEnum(): String {
   return when {
     // name and ordinal are forbidden because already used in Kotlin
     // See https://kotlinlang.org/docs/enum-classes.html#working-with-enum-constants:~:text=properties%20for%20obtaining%20its%20name%20and%20position
-    "(?:name|ordinal)_*".toRegex().matches(this) -> "${this}_"
-    else -> escapeTypeReservedWord() ?: escapeKotlinReservedWord()
+    KOTLIN_ENUM_RESERVED_WORDS_REGEX.matches(this) -> "${this}_"
+    else -> escapeTypeReservedWord() ?: escapeCompanionReservedWord() ?: escapeKotlinReservedWord()
   }
 }
 
 fun String.escapeKotlinReservedWordInSealedClass(): String {
-  return escapeTypeReservedWord() ?: escapeKotlinReservedWord()
+  return escapeTypeReservedWord() ?: escapeCompanionReservedWord() ?: escapeKotlinReservedWord()
 }
diff --git a/tests/enums/src/main/graphql/schema.graphqls b/tests/enums/src/main/graphql/schema.graphqls
index 27e5b0e66bb..3372f4a30ad 100644
--- a/tests/enums/src/main/graphql/schema.graphqls
+++ b/tests/enums/src/main/graphql/schema.graphqls
@@ -20,6 +20,7 @@ enum Direction {
   # Value names should be escaped with _ suffixes when generating enums
   name,
   ordinal,
+  Companion,
 }
 
 enum Gravity {
@@ -32,6 +33,9 @@ enum Gravity {
   LEFT,
   RIGHT,
 
+  # Value names should be escaped with _ suffixes when generating sealed classes
+  Companion,
+
   # Value names should not be escaped when generating sealed classes
   name,
   ordinal,
diff --git a/tests/enums/src/test/kotlin/test/EnumsTest.kt b/tests/enums/src/test/kotlin/test/EnumsTest.kt
index ec64bccb037..5fba7faa9ca 100644
--- a/tests/enums/src/test/kotlin/test/EnumsTest.kt
+++ b/tests/enums/src/test/kotlin/test/EnumsTest.kt
@@ -17,6 +17,7 @@ class EnumsTest {
     assertEquals(Direction.name_, Direction.safeValueOf("name"))
     assertEquals(Direction.ordinal_, Direction.safeValueOf("ordinal"))
     assertEquals(Direction.type__, Direction.safeValueOf("type"))
+    assertEquals(Direction.Companion_, Direction.safeValueOf("Companion"))
   }
 
   @Test
@@ -27,6 +28,7 @@ class EnumsTest {
     assertEquals(Gravity.name, Gravity.safeValueOf("name"))
     assertEquals(Gravity.ordinal, Gravity.safeValueOf("ordinal"))
     assertEquals(Gravity.type__, Gravity.safeValueOf("type"))
+    assertEquals(Gravity.Companion_, Gravity.safeValueOf("Companion"))
   }
 
   @Test
@@ -37,6 +39,7 @@ class EnumsTest {
     assertEquals(enums.java.type.Direction.name, enums.java.type.Direction.safeValueOf("name"))
     assertEquals(enums.java.type.Direction.ordinal, enums.java.type.Direction.safeValueOf("ordinal"))
     assertEquals(enums.java.type.Direction.type__, enums.java.type.Direction.safeValueOf("type"))
+    assertEquals(enums.java.type.Direction.Companion, enums.java.type.Direction.safeValueOf("Companion"))
   }
 
   @Test
@@ -47,6 +50,7 @@ class EnumsTest {
     assertEquals(enums.java.type.Gravity.name, enums.java.type.Gravity.safeValueOf("name"))
     assertEquals(enums.java.type.Gravity.ordinal, enums.java.type.Gravity.safeValueOf("ordinal"))
     assertEquals(enums.java.type.Gravity.type__, enums.java.type.Gravity.safeValueOf("type"))
+    assertEquals(enums.java.type.Gravity.Companion, enums.java.type.Gravity.safeValueOf("Companion"))
   }
 
 
@@ -76,6 +80,7 @@ class EnumsTest {
             Gravity.BOTTOM,
             Gravity.LEFT,
             Gravity.RIGHT,
+            Gravity.Companion_,
             Gravity.name,
             Gravity.ordinal,
             Gravity.type__,