diff --git a/src/execution/__tests__/executor-test.ts b/src/execution/__tests__/executor-test.ts
index b886270978..5283aa4de5 100644
--- a/src/execution/__tests__/executor-test.ts
+++ b/src/execution/__tests__/executor-test.ts
@@ -94,7 +94,7 @@ describe('Execute: Handles basic execution tasks', () => {
       return Promise.resolve(data);
     }
 
-    const DataType = new GraphQLObjectType({
+    const DataType: GraphQLObjectType = new GraphQLObjectType({
       name: 'DataType',
       fields: () => ({
         a: { type: GraphQLString },
@@ -185,7 +185,7 @@ describe('Execute: Handles basic execution tasks', () => {
   });
 
   it('merges parallel fragments', () => {
-    const Type = new GraphQLObjectType({
+    const Type: GraphQLObjectType = new GraphQLObjectType({
       name: 'Type',
       fields: () => ({
         a: { type: GraphQLString, resolve: () => 'Apple' },
@@ -624,7 +624,7 @@ describe('Execute: Handles basic execution tasks', () => {
   });
 
   it('Full response path is included for non-nullable fields', () => {
-    const A = new GraphQLObjectType({
+    const A: GraphQLObjectType = new GraphQLObjectType({
       name: 'A',
       fields: () => ({
         nullableA: {
diff --git a/src/execution/__tests__/schema-test.ts b/src/execution/__tests__/schema-test.ts
index 7da7849c5a..b954fd98db 100644
--- a/src/execution/__tests__/schema-test.ts
+++ b/src/execution/__tests__/schema-test.ts
@@ -29,7 +29,7 @@ describe('Execute: Handles execution with a complex schema', () => {
       },
     });
 
-    const BlogAuthor = new GraphQLObjectType({
+    const BlogAuthor: GraphQLObjectType = new GraphQLObjectType({
       name: 'Author',
       fields: () => ({
         id: { type: GraphQLString },
diff --git a/src/execution/__tests__/union-interface-test.ts b/src/execution/__tests__/union-interface-test.ts
index d65ada60c5..7ff9bd72bb 100644
--- a/src/execution/__tests__/union-interface-test.ts
+++ b/src/execution/__tests__/union-interface-test.ts
@@ -65,14 +65,14 @@ const NamedType = new GraphQLInterfaceType({
   },
 });
 
-const LifeType = new GraphQLInterfaceType({
+const LifeType: GraphQLInterfaceType = new GraphQLInterfaceType({
   name: 'Life',
   fields: () => ({
     progeny: { type: new GraphQLList(LifeType) },
   }),
 });
 
-const MammalType = new GraphQLInterfaceType({
+const MammalType: GraphQLInterfaceType = new GraphQLInterfaceType({
   name: 'Mammal',
   interfaces: [LifeType],
   fields: () => ({
@@ -82,7 +82,7 @@ const MammalType = new GraphQLInterfaceType({
   }),
 });
 
-const DogType = new GraphQLObjectType({
+const DogType: GraphQLObjectType = new GraphQLObjectType({
   name: 'Dog',
   interfaces: [MammalType, LifeType, NamedType],
   fields: () => ({
@@ -95,7 +95,7 @@ const DogType = new GraphQLObjectType({
   isTypeOf: (value) => value instanceof Dog,
 });
 
-const CatType = new GraphQLObjectType({
+const CatType: GraphQLObjectType = new GraphQLObjectType({
   name: 'Cat',
   interfaces: [MammalType, LifeType, NamedType],
   fields: () => ({
@@ -125,7 +125,7 @@ const PetType = new GraphQLUnionType({
   },
 });
 
-const PersonType = new GraphQLObjectType({
+const PersonType: GraphQLObjectType = new GraphQLObjectType({
   name: 'Person',
   interfaces: [NamedType, MammalType, LifeType],
   fields: () => ({
@@ -503,7 +503,7 @@ describe('Execute: Union and intersection types', () => {
     let encounteredSchema;
     let encounteredRootValue;
 
-    const NamedType2 = new GraphQLInterfaceType({
+    const NamedType2: GraphQLInterfaceType = new GraphQLInterfaceType({
       name: 'Named',
       fields: {
         name: { type: GraphQLString },
@@ -516,7 +516,7 @@ describe('Execute: Union and intersection types', () => {
       },
     });
 
-    const PersonType2 = new GraphQLObjectType({
+    const PersonType2: GraphQLObjectType = new GraphQLObjectType({
       name: 'Person',
       interfaces: [NamedType2],
       fields: {
diff --git a/src/execution/__tests__/variables-test.ts b/src/execution/__tests__/variables-test.ts
index ad71465568..ebf7d0b169 100644
--- a/src/execution/__tests__/variables-test.ts
+++ b/src/execution/__tests__/variables-test.ts
@@ -7,7 +7,10 @@ import { invariant } from '../../jsutils/invariant';
 import { Kind } from '../../language/kinds';
 import { parse } from '../../language/parser';
 
-import type { GraphQLArgumentConfig } from '../../type/definition';
+import type {
+  GraphQLFieldConfig,
+  GraphQLArgumentConfig,
+} from '../../type/definition';
 import { GraphQLSchema } from '../../type/schema';
 import { GraphQLString } from '../../type/scalars';
 import {
@@ -64,7 +67,9 @@ const TestEnum = new GraphQLEnumType({
   },
 });
 
-function fieldWithInputArg(inputArg: GraphQLArgumentConfig) {
+function fieldWithInputArg(
+  inputArg: GraphQLArgumentConfig,
+): GraphQLFieldConfig<any, any> {
   return {
     type: GraphQLString,
     args: { input: inputArg },
diff --git a/src/execution/execute.ts b/src/execution/execute.ts
index 923d018d1a..5d7f25e722 100644
--- a/src/execution/execute.ts
+++ b/src/execution/execute.ts
@@ -180,7 +180,7 @@ export function execute(args: ExecutionArgs): PromiseOrValue<ExecutionResult> {
   );
 
   // Return early errors if execution context failed.
-  if (Array.isArray(exeContext)) {
+  if (!('schema' in exeContext)) {
     return { errors: exeContext };
   }
 
@@ -191,9 +191,7 @@ export function execute(args: ExecutionArgs): PromiseOrValue<ExecutionResult> {
   // field and its descendants will be omitted, and sibling fields will still
   // be executed. An execution which encounters errors will still result in a
   // resolved Promise.
-  // @ts-expect-error FIXME: TS Conversion
   const data = executeOperation(exeContext, exeContext.operation, rootValue);
-  // @ts-expect-error FIXME: TS Conversion
   return buildResponse(exeContext, data);
 }
 
diff --git a/src/execution/values.ts b/src/execution/values.ts
index 05277f3827..6d4c95b85a 100644
--- a/src/execution/values.ts
+++ b/src/execution/values.ts
@@ -77,7 +77,7 @@ function coerceVariableValues(
   inputs: { readonly [variable: string]: unknown },
   onError: (error: GraphQLError) => void,
 ): { [variable: string]: unknown } {
-  const coercedValues = {};
+  const coercedValues: { [variable: string]: unknown } = {};
   for (const varDefNode of varDefNodes) {
     const varName = varDefNode.variable.name.value;
     const varType = typeFromAST(schema, varDefNode.type);
@@ -162,7 +162,7 @@ export function getArgumentValues(
   node: FieldNode | DirectiveNode,
   variableValues?: Maybe<ObjMap<unknown>>,
 ): { [argument: string]: unknown } {
-  const coercedValues = {};
+  const coercedValues: { [argument: string]: unknown } = {};
 
   // istanbul ignore next (See: 'https://github.com/graphql/graphql-js/issues/2203')
   const argumentNodes = node.arguments ?? [];