diff --git a/UPGRADE.md b/UPGRADE.md
index b99c034c8cd..339886657a9 100644
--- a/UPGRADE.md
+++ b/UPGRADE.md
@@ -1,3 +1,15 @@
+# Upgrade to 3.1
+
+## Deprecate array access
+
+Use array access on instances of the following classes is deprecated:
+
+- `Doctrine\ORM\Mapping\DiscriminatorColumnMapping`
+- `Doctrine\ORM\Mapping\EmbedClassMapping`
+- `Doctrine\ORM\Mapping\FieldMapping`
+- `Doctrine\ORM\Mapping\JoinColumnMapping`
+- `Doctrine\ORM\Mapping\JoinTableMapping`
+
 # Upgrade to 3.0
 
 ## BC BREAK: `Doctrine\ORM\Proxy\Autoloader` no longer extends `Doctrine\Common\Proxy\Autoloader`
diff --git a/src/Mapping/ArrayAccessImplementation.php b/src/Mapping/ArrayAccessImplementation.php
index e740db8409e..3fd0988cf1b 100644
--- a/src/Mapping/ArrayAccessImplementation.php
+++ b/src/Mapping/ArrayAccessImplementation.php
@@ -4,6 +4,7 @@
 
 namespace Doctrine\ORM\Mapping;
 
+use Doctrine\Deprecations\Deprecation;
 use InvalidArgumentException;
 
 use function property_exists;
@@ -14,12 +15,26 @@ trait ArrayAccessImplementation
     /** @param string $offset */
     public function offsetExists(mixed $offset): bool
     {
+        Deprecation::trigger(
+            'doctrine/orm',
+            'https://github.com/doctrine/orm/pull/11211',
+            'Using ArrayAccess on %s is deprecated and will not be possible in Doctrine ORM 4.0. Use the corresponding property instead.',
+            static::class,
+        );
+
         return isset($this->$offset);
     }
 
     /** @param string $offset */
     public function offsetGet(mixed $offset): mixed
     {
+        Deprecation::trigger(
+            'doctrine/orm',
+            'https://github.com/doctrine/orm/pull/11211',
+            'Using ArrayAccess on %s is deprecated and will not be possible in Doctrine ORM 4.0. Use the corresponding property instead.',
+            static::class,
+        );
+
         if (! property_exists($this, $offset)) {
             throw new InvalidArgumentException('Undefined property: ' . $offset);
         }
@@ -30,12 +45,26 @@ public function offsetGet(mixed $offset): mixed
     /** @param string $offset */
     public function offsetSet(mixed $offset, mixed $value): void
     {
+        Deprecation::trigger(
+            'doctrine/orm',
+            'https://github.com/doctrine/orm/pull/11211',
+            'Using ArrayAccess on %s is deprecated and will not be possible in Doctrine ORM 4.0. Use the corresponding property instead.',
+            static::class,
+        );
+
         $this->$offset = $value;
     }
 
     /** @param string $offset */
     public function offsetUnset(mixed $offset): void
     {
+        Deprecation::trigger(
+            'doctrine/orm',
+            'https://github.com/doctrine/orm/pull/11211',
+            'Using ArrayAccess on %s is deprecated and will not be possible in Doctrine ORM 4.0. Use the corresponding property instead.',
+            static::class,
+        );
+
         $this->$offset = null;
     }
 }
diff --git a/src/Persisters/Entity/JoinedSubclassPersister.php b/src/Persisters/Entity/JoinedSubclassPersister.php
index 10eb31ec50b..76719a2c275 100644
--- a/src/Persisters/Entity/JoinedSubclassPersister.php
+++ b/src/Persisters/Entity/JoinedSubclassPersister.php
@@ -466,7 +466,7 @@ protected function getInsertColumnList(): array
                     || isset($this->class->associationMappings[$name]->inherited)
                     || ($this->class->isVersioned && $this->class->versionField === $name)
                     || isset($this->class->embeddedClasses[$name])
-                    || isset($this->class->fieldMappings[$name]['notInsertable'])
+                    || isset($this->class->fieldMappings[$name]->notInsertable)
             ) {
                 continue;
             }
@@ -519,9 +519,9 @@ protected function fetchVersionAndNotUpsertableValues(ClassMetadata $versionedCl
             $class = null;
             if ($this->class->isVersioned && $key === $versionedClass->versionField) {
                 $class = $versionedClass;
-            } elseif (isset($column['generated'])) {
-                $class = isset($column['inherited'])
-                    ? $this->em->getClassMetadata($column['inherited'])
+            } elseif (isset($column->generated)) {
+                $class = isset($column->inherited)
+                    ? $this->em->getClassMetadata($column->inherited)
                     : $this->class;
             } else {
                 continue;
diff --git a/src/Query/ResultSetMappingBuilder.php b/src/Query/ResultSetMappingBuilder.php
index 2e81db7d71b..f28f3a9c005 100644
--- a/src/Query/ResultSetMappingBuilder.php
+++ b/src/Query/ResultSetMappingBuilder.php
@@ -134,7 +134,7 @@ protected function addAllClassFields(string $class, string $alias, array $column
 
             $this->addFieldResult($alias, $columnAlias, $propertyName);
 
-            $enumType = $classMetadata->getFieldMapping($propertyName)['enumType'] ?? null;
+            $enumType = $classMetadata->getFieldMapping($propertyName)->enumType ?? null;
             if (! empty($enumType)) {
                 $this->addEnumResult($columnAlias, $enumType);
             }
diff --git a/src/Tools/SchemaValidator.php b/src/Tools/SchemaValidator.php
index 687fd1d36ba..43b10ee3983 100644
--- a/src/Tools/SchemaValidator.php
+++ b/src/Tools/SchemaValidator.php
@@ -343,7 +343,7 @@ function (FieldMapping $fieldMapping) use ($class): string|null {
                             return null;
                         }
 
-                        $metadataFieldType = $this->findBuiltInType(Type::getType($fieldMapping['type']));
+                        $metadataFieldType = $this->findBuiltInType(Type::getType($fieldMapping->type));
 
                         //If the metadata field type is not a mapped built-in type, we cannot check it
                         if ($metadataFieldType === null) {
@@ -371,7 +371,7 @@ function (FieldMapping $fieldMapping) use ($class): string|null {
                                 );
                             }
 
-                            if (! isset($fieldMapping['enumType']) || $propertyType === $fieldMapping['enumType']) {
+                            if (! isset($fieldMapping->enumType) || $propertyType === $fieldMapping->enumType) {
                                 return null;
                             }
 
@@ -380,17 +380,17 @@ function (FieldMapping $fieldMapping) use ($class): string|null {
                                 $class->name,
                                 $fieldName,
                                 $propertyType,
-                                $fieldMapping['enumType'],
+                                $fieldMapping->enumType,
                             );
                         }
 
                         if (
-                            isset($fieldMapping['enumType'])
-                            && $propertyType !== $fieldMapping['enumType']
+                            isset($fieldMapping->enumType)
+                            && $propertyType !== $fieldMapping->enumType
                             && interface_exists($propertyType)
-                            && is_a($fieldMapping['enumType'], $propertyType, true)
+                            && is_a($fieldMapping->enumType, $propertyType, true)
                         ) {
-                            $backingType = (string) (new ReflectionEnum($fieldMapping['enumType']))->getBackingType();
+                            $backingType = (string) (new ReflectionEnum($fieldMapping->enumType))->getBackingType();
 
                             if ($metadataFieldType === $backingType) {
                                 return null;
@@ -400,14 +400,14 @@ function (FieldMapping $fieldMapping) use ($class): string|null {
                                 "The field '%s#%s' has the metadata enumType '%s' with a backing type of '%s' that differs from the metadata field type '%s'.",
                                 $class->name,
                                 $fieldName,
-                                $fieldMapping['enumType'],
+                                $fieldMapping->enumType,
                                 $backingType,
                                 $metadataFieldType,
                             );
                         }
 
                         if (
-                            $fieldMapping['type'] === 'json'
+                            $fieldMapping->type === 'json'
                             && in_array($propertyType, ['string', 'int', 'float', 'bool', 'true', 'false', 'null'], true)
                         ) {
                             return null;
@@ -419,7 +419,7 @@ function (FieldMapping $fieldMapping) use ($class): string|null {
                             $fieldName,
                             $propertyType,
                             $metadataFieldType,
-                            $fieldMapping['type'],
+                            $fieldMapping->type,
                         );
                     },
                     $class->fieldMappings,
diff --git a/src/UnitOfWork.php b/src/UnitOfWork.php
index 37fcf71253c..f82a9afc055 100644
--- a/src/UnitOfWork.php
+++ b/src/UnitOfWork.php
@@ -997,7 +997,7 @@ public function recomputeSingleEntityChangeSet(ClassMetadata $class, object $ent
         foreach ($actualData as $propName => $actualValue) {
             $orgValue = $originalData[$propName] ?? null;
 
-            if (isset($class->fieldMappings[$propName]['enumType'])) {
+            if (isset($class->fieldMappings[$propName]->enumType)) {
                 if (is_array($orgValue)) {
                     foreach ($orgValue as $id => $val) {
                         if ($val instanceof BackedEnum) {
@@ -1267,16 +1267,16 @@ private function computeDeleteExecutionOrder(): array
                 }
 
                 $joinColumns = reset($assoc->joinColumns);
-                if (! isset($joinColumns['onDelete'])) {
+                if (! isset($joinColumns->onDelete)) {
                     continue;
                 }
 
-                $onDeleteOption = strtolower($joinColumns['onDelete']);
+                $onDeleteOption = strtolower($joinColumns->onDelete);
                 if ($onDeleteOption !== 'cascade') {
                     continue;
                 }
 
-                $targetEntity = $class->getFieldValue($entity, $assoc['fieldName']);
+                $targetEntity = $class->getFieldValue($entity, $assoc->fieldName);
 
                 // If the association does not refer to another entity or that entity
                 // is not to be deleted, there is no ordering problem and we can
diff --git a/tests/Tests/ORM/Functional/Ticket/GH11135Test.php b/tests/Tests/ORM/Functional/Ticket/GH11135Test.php
index 1afc872fd2d..ae514cfaa4f 100644
--- a/tests/Tests/ORM/Functional/Ticket/GH11135Test.php
+++ b/tests/Tests/ORM/Functional/Ticket/GH11135Test.php
@@ -25,8 +25,8 @@ public function testOverrideInheritsDeclaringClass(): void
         $cm1 = $this->_em->getClassMetadata(GH11135EntityWithOverride::class);
         $cm2 = $this->_em->getClassMetadata(GH11135EntityWithoutOverride::class);
 
-        self::assertSame($cm1->getFieldMapping('id')['declared'], $cm2->getFieldMapping('id')['declared']);
-        self::assertSame($cm1->getAssociationMapping('ref')['declared'], $cm2->getAssociationMapping('ref')['declared']);
+        self::assertSame($cm1->getFieldMapping('id')->declared, $cm2->getFieldMapping('id')->declared);
+        self::assertSame($cm1->getAssociationMapping('ref')->declared, $cm2->getAssociationMapping('ref')->declared);
     }
 }
 
diff --git a/tests/Tests/ORM/Mapping/ClassMetadataTest.php b/tests/Tests/ORM/Mapping/ClassMetadataTest.php
index edd05959408..1ce384b5249 100644
--- a/tests/Tests/ORM/Mapping/ClassMetadataTest.php
+++ b/tests/Tests/ORM/Mapping/ClassMetadataTest.php
@@ -859,8 +859,7 @@ public function testAttributeOverrideKeepsDeclaringClass(): void
 
         $mapping = $cm->getFieldMapping('id');
 
-        self::assertArrayHasKey('declared', $mapping);
-        self::assertSame(AbstractContentItem::class, $mapping['declared']);
+        self::assertSame(AbstractContentItem::class, $mapping->declared);
     }
 
     public function testAssociationOverrideKeepsDeclaringClass(): void
diff --git a/tests/Tests/ORM/Mapping/XmlMappingDriverTest.php b/tests/Tests/ORM/Mapping/XmlMappingDriverTest.php
index 86e6fde2cf5..5426da45c91 100644
--- a/tests/Tests/ORM/Mapping/XmlMappingDriverTest.php
+++ b/tests/Tests/ORM/Mapping/XmlMappingDriverTest.php
@@ -297,8 +297,8 @@ public function testClassNameInFieldOrId(): void
         /** @var array{type: string} $name */
         $name = $class->getFieldMapping('name');
 
-        self::assertEquals(ProjectId::class, $id['type']);
-        self::assertEquals(ProjectName::class, $name['type']);
+        self::assertEquals(ProjectId::class, $id->type);
+        self::assertEquals(ProjectName::class, $name->type);
     }
 
     public function testDisablingXmlValidationIsPossible(): void