diff --git a/packages/react-native/ReactCommon/jsi/jsi/decorator.h b/packages/react-native/ReactCommon/jsi/jsi/decorator.h
index f101c1832e61..4bc4f18caa44 100644
--- a/packages/react-native/ReactCommon/jsi/jsi/decorator.h
+++ b/packages/react-native/ReactCommon/jsi/jsi/decorator.h
@@ -210,6 +210,9 @@ class RuntimeDecorator : public Base, private jsi::Instrumentation {
   BigInt createBigIntFromUint64(uint64_t value) override {
     return plain_.createBigIntFromUint64(value);
   }
+  BigInt createBigIntFromBytes(const uint8_t* bytes, size_t length) override {
+    return plain_.createBigIntFromBytes(bytes, length);
+  }
   bool bigintIsInt64(const BigInt& b) override {
     return plain_.bigintIsInt64(b);
   }
@@ -222,6 +225,9 @@ class RuntimeDecorator : public Base, private jsi::Instrumentation {
   String bigintToString(const BigInt& bigint, int radix) override {
     return plain_.bigintToString(bigint, radix);
   }
+  std::vector<uint8_t> bytes(const BigInt& b) override {
+    return plain_.bytes(b);
+  }
 
   String createStringFromAscii(const char* str, size_t length) override {
     return plain_.createStringFromAscii(str, length);
@@ -779,6 +785,10 @@ class WithRuntimeDecorator : public RuntimeDecorator<Plain, Base> {
     Around around{with_};
     return RD::createBigIntFromUint64(i);
   }
+  BigInt createBigIntFromBytes(const uint8_t* bytes, size_t length) override {
+    Around around{with_};
+    return RD::createBigIntFromBytes(bytes, length);
+  }
   bool bigintIsInt64(const BigInt& bi) override {
     Around around{with_};
     return RD::bigintIsInt64(bi);
@@ -795,6 +805,10 @@ class WithRuntimeDecorator : public RuntimeDecorator<Plain, Base> {
     Around around{with_};
     return RD::bigintToString(bi, i);
   }
+  std::vector<uint8_t> bytes(const BigInt& bi) override {
+    Around around{with_};
+    return RD::bytes(bi);
+  }
 
   String createStringFromAscii(const char* str, size_t length) override {
     Around around{with_};
diff --git a/packages/react-native/ReactCommon/jsi/jsi/jsi.cpp b/packages/react-native/ReactCommon/jsi/jsi/jsi.cpp
index 792b5bf5a0bf..6536372194ab 100644
--- a/packages/react-native/ReactCommon/jsi/jsi/jsi.cpp
+++ b/packages/react-native/ReactCommon/jsi/jsi/jsi.cpp
@@ -606,6 +606,17 @@ size_t Runtime::length(const String& str) {
   return utf16(str).size();
 }
 
+BigInt Runtime::createBigIntFromBytes(
+    const uint8_t* /*bytes*/,
+    size_t /*length*/) {
+  throw JSINativeException(
+      "createBigIntFromBytes is not implemented by this runtime");
+}
+
+std::vector<uint8_t> Runtime::bytes(const BigInt& /*bigint*/) {
+  throw JSINativeException("BigInt.bytes is not implemented by this runtime");
+}
+
 bool Runtime::detached(const ArrayBuffer& buffer) {
   Value prop = buffer.getProperty(*this, "detached");
   if (!prop.isBool()) {
diff --git a/packages/react-native/ReactCommon/jsi/jsi/jsi.h b/packages/react-native/ReactCommon/jsi/jsi/jsi.h
index bf98028fb3fb..aaa17ae90982 100644
--- a/packages/react-native/ReactCommon/jsi/jsi/jsi.h
+++ b/packages/react-native/ReactCommon/jsi/jsi/jsi.h
@@ -498,10 +498,17 @@ class JSI_EXPORT IRuntime : public ICast {
 
   virtual BigInt createBigIntFromInt64(int64_t) = 0;
   virtual BigInt createBigIntFromUint64(uint64_t) = 0;
+  /// Create a BigInt from a raw byte sequence \p bytes of \p length, which
+  /// provides the BigInt data in little-endian, two's complement
+  /// representation. The data is copied.
+  virtual BigInt createBigIntFromBytes(const uint8_t* bytes, size_t length) = 0;
   virtual bool bigintIsInt64(const BigInt&) = 0;
   virtual bool bigintIsUint64(const BigInt&) = 0;
   virtual uint64_t truncate(const BigInt&) = 0;
   virtual String bigintToString(const BigInt&, int) = 0;
+  /// Returns the raw byte representation of a BigInt in little-endian, two's
+  /// complement representation.
+  virtual std::vector<uint8_t> bytes(const BigInt&) = 0;
 
   virtual String createStringFromAscii(const char* str, size_t length) = 0;
   virtual String createStringFromUtf8(const uint8_t* utf8, size_t length) = 0;
@@ -793,6 +800,9 @@ class JSI_EXPORT Runtime : public IRuntime {
 
   size_t length(const String& str) override;
 
+  BigInt createBigIntFromBytes(const uint8_t* bytes, size_t length) override;
+  std::vector<uint8_t> bytes(const BigInt&) override;
+
  protected:
   friend class Pointer;
   friend class PropNameID;
@@ -1004,6 +1014,20 @@ class JSI_EXPORT BigInt : public Pointer {
     return runtime.createBigIntFromUint64(value);
   }
 
+  /// Create a BigInt from a raw byte sequence \p bytes of \p length, which
+  /// provides the BigInt data in little-endian, two's complement
+  /// representation. The data is copied.
+  static BigInt
+  fromBytes(IRuntime& runtime, const uint8_t* bytes, size_t length) {
+    return runtime.createBigIntFromBytes(bytes, length);
+  }
+
+  /// Returns the raw byte representation of a BigInt in little-endian, two's
+  /// complement representation.
+  std::vector<uint8_t> bytes(IRuntime& runtime) const {
+    return runtime.bytes(*this);
+  }
+
   /// \return whether a === b.
   static bool
   strictEquals(IRuntime& runtime, const BigInt& a, const BigInt& b) {