diff --git a/src/lib/esnext.intl.d.ts b/src/lib/esnext.intl.d.ts
index 95608636119c4..2f2f021f8750e 100644
--- a/src/lib/esnext.intl.d.ts
+++ b/src/lib/esnext.intl.d.ts
@@ -7,6 +7,6 @@ declare namespace Intl {
     }
 
     interface NumberFormat {
-        formatToParts(number?: number): NumberFormatPart[];
+        formatToParts(number?: number | bigint): NumberFormatPart[];
     }
 }
diff --git a/tests/baselines/reference/formatToPartsBigInt.js b/tests/baselines/reference/formatToPartsBigInt.js
new file mode 100644
index 0000000000000..1c53ccb24de6c
--- /dev/null
+++ b/tests/baselines/reference/formatToPartsBigInt.js
@@ -0,0 +1,13 @@
+//// [formatToPartsBigInt.ts]
+// Intl.NumberFormat.formatToParts should support bigInt
+
+// Test Intl methods with new parameter type
+new Intl.NumberFormat("fr").formatToParts(3000n);
+new Intl.NumberFormat("fr").formatToParts(BigInt(123));
+
+
+//// [formatToPartsBigInt.js]
+// Intl.NumberFormat.formatToParts should support bigInt
+// Test Intl methods with new parameter type
+new Intl.NumberFormat("fr").formatToParts(3000n);
+new Intl.NumberFormat("fr").formatToParts(BigInt(123));
diff --git a/tests/baselines/reference/formatToPartsBigInt.symbols b/tests/baselines/reference/formatToPartsBigInt.symbols
new file mode 100644
index 0000000000000..f3037bfef10ed
--- /dev/null
+++ b/tests/baselines/reference/formatToPartsBigInt.symbols
@@ -0,0 +1,19 @@
+=== tests/cases/compiler/formatToPartsBigInt.ts ===
+// Intl.NumberFormat.formatToParts should support bigInt
+
+// Test Intl methods with new parameter type
+new Intl.NumberFormat("fr").formatToParts(3000n);
+>new Intl.NumberFormat("fr").formatToParts : Symbol(Intl.NumberFormat.formatToParts, Decl(lib.esnext.intl.d.ts, --, --))
+>Intl.NumberFormat : Symbol(Intl.NumberFormat, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es2020.bigint.d.ts, --, --), Decl(lib.esnext.intl.d.ts, --, --))
+>Intl : Symbol(Intl, Decl(lib.es5.d.ts, --, --), Decl(lib.es2017.intl.d.ts, --, --), Decl(lib.es2018.intl.d.ts, --, --), Decl(lib.es2020.bigint.d.ts, --, --), Decl(lib.es2020.intl.d.ts, --, --) ... and 1 more)
+>NumberFormat : Symbol(Intl.NumberFormat, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es2020.bigint.d.ts, --, --), Decl(lib.esnext.intl.d.ts, --, --))
+>formatToParts : Symbol(Intl.NumberFormat.formatToParts, Decl(lib.esnext.intl.d.ts, --, --))
+
+new Intl.NumberFormat("fr").formatToParts(BigInt(123));
+>new Intl.NumberFormat("fr").formatToParts : Symbol(Intl.NumberFormat.formatToParts, Decl(lib.esnext.intl.d.ts, --, --))
+>Intl.NumberFormat : Symbol(Intl.NumberFormat, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es2020.bigint.d.ts, --, --), Decl(lib.esnext.intl.d.ts, --, --))
+>Intl : Symbol(Intl, Decl(lib.es5.d.ts, --, --), Decl(lib.es2017.intl.d.ts, --, --), Decl(lib.es2018.intl.d.ts, --, --), Decl(lib.es2020.bigint.d.ts, --, --), Decl(lib.es2020.intl.d.ts, --, --) ... and 1 more)
+>NumberFormat : Symbol(Intl.NumberFormat, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es2020.bigint.d.ts, --, --), Decl(lib.esnext.intl.d.ts, --, --))
+>formatToParts : Symbol(Intl.NumberFormat.formatToParts, Decl(lib.esnext.intl.d.ts, --, --))
+>BigInt : Symbol(BigInt, Decl(lib.es2020.bigint.d.ts, --, --), Decl(lib.es2020.bigint.d.ts, --, --))
+
diff --git a/tests/baselines/reference/formatToPartsBigInt.types b/tests/baselines/reference/formatToPartsBigInt.types
new file mode 100644
index 0000000000000..fc911ed065711
--- /dev/null
+++ b/tests/baselines/reference/formatToPartsBigInt.types
@@ -0,0 +1,28 @@
+=== tests/cases/compiler/formatToPartsBigInt.ts ===
+// Intl.NumberFormat.formatToParts should support bigInt
+
+// Test Intl methods with new parameter type
+new Intl.NumberFormat("fr").formatToParts(3000n);
+>new Intl.NumberFormat("fr").formatToParts(3000n) : Intl.NumberFormatPart[]
+>new Intl.NumberFormat("fr").formatToParts : (number?: number | bigint) => Intl.NumberFormatPart[]
+>new Intl.NumberFormat("fr") : Intl.NumberFormat
+>Intl.NumberFormat : { (locales?: string | string[], options?: Intl.NumberFormatOptions): Intl.NumberFormat; new (locales?: string | string[], options?: Intl.NumberFormatOptions): Intl.NumberFormat; supportedLocalesOf(locales: string | string[], options?: Intl.NumberFormatOptions): string[]; }
+>Intl : typeof Intl
+>NumberFormat : { (locales?: string | string[], options?: Intl.NumberFormatOptions): Intl.NumberFormat; new (locales?: string | string[], options?: Intl.NumberFormatOptions): Intl.NumberFormat; supportedLocalesOf(locales: string | string[], options?: Intl.NumberFormatOptions): string[]; }
+>"fr" : "fr"
+>formatToParts : (number?: number | bigint) => Intl.NumberFormatPart[]
+>3000n : 3000n
+
+new Intl.NumberFormat("fr").formatToParts(BigInt(123));
+>new Intl.NumberFormat("fr").formatToParts(BigInt(123)) : Intl.NumberFormatPart[]
+>new Intl.NumberFormat("fr").formatToParts : (number?: number | bigint) => Intl.NumberFormatPart[]
+>new Intl.NumberFormat("fr") : Intl.NumberFormat
+>Intl.NumberFormat : { (locales?: string | string[], options?: Intl.NumberFormatOptions): Intl.NumberFormat; new (locales?: string | string[], options?: Intl.NumberFormatOptions): Intl.NumberFormat; supportedLocalesOf(locales: string | string[], options?: Intl.NumberFormatOptions): string[]; }
+>Intl : typeof Intl
+>NumberFormat : { (locales?: string | string[], options?: Intl.NumberFormatOptions): Intl.NumberFormat; new (locales?: string | string[], options?: Intl.NumberFormatOptions): Intl.NumberFormat; supportedLocalesOf(locales: string | string[], options?: Intl.NumberFormatOptions): string[]; }
+>"fr" : "fr"
+>formatToParts : (number?: number | bigint) => Intl.NumberFormatPart[]
+>BigInt(123) : bigint
+>BigInt : BigIntConstructor
+>123 : 123
+
diff --git a/tests/cases/compiler/formatToPartsBigInt.ts b/tests/cases/compiler/formatToPartsBigInt.ts
new file mode 100644
index 0000000000000..6b50e98b8b6ea
--- /dev/null
+++ b/tests/cases/compiler/formatToPartsBigInt.ts
@@ -0,0 +1,7 @@
+// @target: esnext
+
+// Intl.NumberFormat.formatToParts should support bigInt
+
+// Test Intl methods with new parameter type
+new Intl.NumberFormat("fr").formatToParts(3000n);
+new Intl.NumberFormat("fr").formatToParts(BigInt(123));