diff --git a/e2e/__tests__/__snapshots__/logger.test.ts.snap b/e2e/__tests__/__snapshots__/logger.test.ts.snap
index c4060d043f..0f10b2138a 100644
--- a/e2e/__tests__/__snapshots__/logger.test.ts.snap
+++ b/e2e/__tests__/__snapshots__/logger.test.ts.snap
@@ -127,63 +127,6 @@ Array [
 ]
 `;
 
-exports[`ts-jest logging deprecation warning with astTransformers config as string array should pass using template "default" 1`] = `
-  √ jest
-  ↳ exit code: 0
-  ===[ STDOUT ]===================================================================
-  
-  ===[ STDERR ]===================================================================
-  ts-jest[config] (WARN) The configuration for astTransformers as string[] is deprecated and will be removed in ts-jest 27. Please define your custom AST transformers in a form of an object. More information you can check online documentation https://kulshekhar.github.io/ts-jest/user/config/astTransformers
-  PASS ./Hello.spec.ts
-    Hello Class
-      √ should create a new Hello
-  
-  Test Suites: 1 passed, 1 total
-  Tests:       1 passed, 1 total
-  Snapshots:   0 total
-  Time:        XXs
-  Ran all test suites.
-  ================================================================================
-`;
-
-exports[`ts-jest logging deprecation warning with astTransformers config as string array should pass using template "with-babel-7" 1`] = `
-  √ jest
-  ↳ exit code: 0
-  ===[ STDOUT ]===================================================================
-  
-  ===[ STDERR ]===================================================================
-  ts-jest[config] (WARN) The configuration for astTransformers as string[] is deprecated and will be removed in ts-jest 27. Please define your custom AST transformers in a form of an object. More information you can check online documentation https://kulshekhar.github.io/ts-jest/user/config/astTransformers
-  PASS ./Hello.spec.ts
-    Hello Class
-      √ should create a new Hello
-  
-  Test Suites: 1 passed, 1 total
-  Tests:       1 passed, 1 total
-  Snapshots:   0 total
-  Time:        XXs
-  Ran all test suites.
-  ================================================================================
-`;
-
-exports[`ts-jest logging deprecation warning with astTransformers config as string array should pass using template "with-babel-7-string-config" 1`] = `
-  √ jest
-  ↳ exit code: 0
-  ===[ STDOUT ]===================================================================
-  
-  ===[ STDERR ]===================================================================
-  ts-jest[config] (WARN) The configuration for astTransformers as string[] is deprecated and will be removed in ts-jest 27. Please define your custom AST transformers in a form of an object. More information you can check online documentation https://kulshekhar.github.io/ts-jest/user/config/astTransformers
-  PASS ./Hello.spec.ts
-    Hello Class
-      √ should create a new Hello
-  
-  Test Suites: 1 passed, 1 total
-  Tests:       1 passed, 1 total
-  Snapshots:   0 total
-  Time:        XXs
-  Ran all test suites.
-  ================================================================================
-`;
-
 exports[`ts-jest logging deprecation warning with packageJson config should pass using template "default" 1`] = `
   √ jest
   ↳ exit code: 0
diff --git a/e2e/__tests__/logger.test.ts b/e2e/__tests__/logger.test.ts
index aa3219f7db..de56f30177 100644
--- a/e2e/__tests__/logger.test.ts
+++ b/e2e/__tests__/logger.test.ts
@@ -92,22 +92,6 @@ describe('ts-jest logging', () => {
   }
 
   describe('deprecation warning', () => {
-    describe('with astTransformers config as string array', () => {
-      const testCase = configureTestCase('simple', {
-        tsJestConfig: {
-          astTransformers: []
-        }
-      })
-
-      testCase.runWithTemplates(allValidPackageSets, 0, (runTest, { testLabel }) => {
-        it(testLabel, () => {
-          const result = runTest()
-          expect(result.status).toBe(0)
-          expect(result).toMatchSnapshot()
-        })
-      })
-    })
-
     describe('with packageJson config', () => {
       const testCase = configureTestCase('simple', {
         tsJestConfig: {
diff --git a/src/config/config-set.spec.ts b/src/config/config-set.spec.ts
index be1aa55eea..5d61f765e0 100644
--- a/src/config/config-set.spec.ts
+++ b/src/config/config-set.spec.ts
@@ -154,8 +154,6 @@ describe('compilerModule', () => {
 }) // compilerModule
 
 describe('customTransformers', () => {
-  const logger = testing.createLoggerMock()
-
   it.each([
     {},
     {
@@ -189,29 +187,6 @@ describe('customTransformers', () => {
 
     expect(cs.customTransformers).toMatchSnapshot()
   })
-
-  it('should return an object containing all resolved transformers when astTransformers config is an array', () => {
-    expect(
-      createConfigSet({
-        jestConfig: {
-          rootDir: 'src',
-          cwd: 'src',
-        } as any,
-        logger,
-        tsJestConfig: {
-          astTransformers: ['<rootDir>/__mocks__/dummy-transformer'],
-        },
-        resolve: null,
-      }).customTransformers,
-    ).toMatchInlineSnapshot(`
-      Object {
-        "before": Array [
-          [Function],
-          [Function],
-        ],
-      }
-    `)
-  })
 })
 
 describe('tsCompiler', () => {
diff --git a/src/config/config-set.ts b/src/config/config-set.ts
index b1d6ef9308..4c4a7e64e7 100644
--- a/src/config/config-set.ts
+++ b/src/config/config-set.ts
@@ -291,49 +291,34 @@ export class ConfigSet {
       before: [hoisting(this)],
     }
     if (astTransformers) {
-      if (Array.isArray(astTransformers)) {
-        this.logger.warn(Deprecations.AstTransformerArrayConfig)
+      const resolveTransformers = (transformers: (string | AstTransformer)[]) =>
+        transformers.map((transformer) => {
+          let transformerPath: string
+          if (typeof transformer === 'string') {
+            transformerPath = this.resolvePath(transformer, { nodeResolve: true })
 
-        this.customTransformers = {
-          before: [
-            ...this.customTransformers.before,
-            ...astTransformers.map((transformer) => {
-              const transformerPath = this.resolvePath(transformer, { nodeResolve: true })
-
-              return require(transformerPath).factory(this)
-            }),
-          ],
-        }
-      } else {
-        const resolveTransformers = (transformers: (string | AstTransformer)[]) =>
-          transformers.map((transformer) => {
-            let transformerPath: string
-            if (typeof transformer === 'string') {
-              transformerPath = this.resolvePath(transformer, { nodeResolve: true })
-
-              return require(transformerPath).factory(this)
-            } else {
-              transformerPath = this.resolvePath(transformer.path, { nodeResolve: true })
+            return require(transformerPath).factory(this)
+          } else {
+            transformerPath = this.resolvePath(transformer.path, { nodeResolve: true })
 
-              return require(transformerPath).factory(this, transformer.options)
-            }
-          })
-        if (astTransformers.before) {
-          this.customTransformers = {
-            before: [...this.customTransformers.before, ...resolveTransformers(astTransformers.before)],
+            return require(transformerPath).factory(this, transformer.options)
           }
+        })
+      if (astTransformers.before) {
+        this.customTransformers = {
+          before: [...this.customTransformers.before, ...resolveTransformers(astTransformers.before)],
         }
-        if (astTransformers.after) {
-          this.customTransformers = {
-            ...this.customTransformers,
-            after: resolveTransformers(astTransformers.after),
-          }
+      }
+      if (astTransformers.after) {
+        this.customTransformers = {
+          ...this.customTransformers,
+          after: resolveTransformers(astTransformers.after),
         }
-        if (astTransformers.afterDeclarations) {
-          this.customTransformers = {
-            ...this.customTransformers,
-            afterDeclarations: resolveTransformers(astTransformers.afterDeclarations),
-          }
+      }
+      if (astTransformers.afterDeclarations) {
+        this.customTransformers = {
+          ...this.customTransformers,
+          afterDeclarations: resolveTransformers(astTransformers.afterDeclarations),
         }
       }
     }
diff --git a/src/types.ts b/src/types.ts
index 82c67133d7..6a5552ebf1 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -83,7 +83,7 @@ export interface TsJestGlobalOptions {
   /**
    * Custom transformers (mostly used by jest presets)
    */
-  astTransformers?: string[] | ConfigCustomTransformer
+  astTransformers?: ConfigCustomTransformer
 
   /**
    * TS diagnostics - less to be reported if `isolatedModules` is `true`. It can be:
diff --git a/src/utils/messages.ts b/src/utils/messages.ts
index 36dae04c9d..d740530d45 100644
--- a/src/utils/messages.ts
+++ b/src/utils/messages.ts
@@ -35,7 +35,6 @@ export const enum Deprecations {
   ConfigOption = '"[jest-config].{{oldPath}}" is deprecated, use "[jest-config].{{newPath}}" instead.',
   ConfigOptionWithNote = '"[jest-config].{{oldPath}}" is deprecated, use "[jest-config].{{newPath}}" instead.\n    ↳ {{note}}',
   ConfigOptionUseBabelRcNote = 'See `babel-jest` related issue: https://github.com/facebook/jest/issues/3845',
-  AstTransformerArrayConfig = 'The configuration for astTransformers as string[] is deprecated and will be removed in ts-jest 27. Please define your custom AST transformers in a form of an object. More information you can check online documentation https://kulshekhar.github.io/ts-jest/user/config/astTransformers',
   PackageJson = 'The option `packageJson` is deprecated and will be removed in ts-jest 27. This option is not used by internal `ts-jest`',
 }