diff --git a/packages/seedless-onboarding-controller/src/SeedlessOnboardingController.ts b/packages/seedless-onboarding-controller/src/SeedlessOnboardingController.ts
index 5a91543ded0..d20536b8c5e 100644
--- a/packages/seedless-onboarding-controller/src/SeedlessOnboardingController.ts
+++ b/packages/seedless-onboarding-controller/src/SeedlessOnboardingController.ts
@@ -38,7 +38,11 @@ import {
   SeedlessOnboardingControllerErrorMessage,
   Web3AuthNetwork,
 } from './constants';
-import { PasswordSyncError, RecoveryError } from './errors';
+import {
+  PasswordSyncError,
+  RecoveryError,
+  SeedlessOnboardingError,
+} from './errors';
 import { projectLogger, createModuleLogger } from './logger';
 import { SecretMetadata } from './SecretMetadata';
 import type {
@@ -437,8 +441,11 @@ export class SeedlessOnboardingController<
         return authenticationResult;
       } catch (error) {
         log('Error authenticating user', error);
-        throw new Error(
+        throw new SeedlessOnboardingError(
           SeedlessOnboardingControllerErrorMessage.AuthenticationError,
+          {
+            cause: error,
+          },
         );
       }
     };
diff --git a/packages/seedless-onboarding-controller/src/errors.test.ts b/packages/seedless-onboarding-controller/src/errors.test.ts
index 0011a44c87f..795280022b0 100644
--- a/packages/seedless-onboarding-controller/src/errors.test.ts
+++ b/packages/seedless-onboarding-controller/src/errors.test.ts
@@ -1,7 +1,10 @@
 import { TOPRFErrorCode } from '@metamask/toprf-secure-backup';
 
 import { SeedlessOnboardingControllerErrorMessage } from './constants';
-import { getErrorMessageFromTOPRFErrorCode } from './errors';
+import {
+  getErrorMessageFromTOPRFErrorCode,
+  SeedlessOnboardingError,
+} from './errors';
 
 describe('getErrorMessageFromTOPRFErrorCode', () => {
   it('returns TooManyLoginAttempts for RateLimitExceeded', () => {
@@ -49,3 +52,159 @@ describe('getErrorMessageFromTOPRFErrorCode', () => {
     ).toBe('fallback');
   });
 });
+
+describe('SeedlessOnboardingError', () => {
+  describe('constructor', () => {
+    it('creates an error with just a message', () => {
+      const error = new SeedlessOnboardingError('Test error message');
+
+      expect(error.message).toBe('Test error message');
+      expect(error.name).toBe('SeedlessOnboardingControllerError');
+      expect(error.details).toBeUndefined();
+      expect(error.cause).toBeUndefined();
+    });
+
+    it('creates an error with a message from SeedlessOnboardingControllerErrorMessage enum', () => {
+      const error = new SeedlessOnboardingError(
+        SeedlessOnboardingControllerErrorMessage.AuthenticationError,
+      );
+
+      expect(error.message).toBe(
+        SeedlessOnboardingControllerErrorMessage.AuthenticationError,
+      );
+      expect(error.name).toBe('SeedlessOnboardingControllerError');
+    });
+
+    it('creates an error with message and details', () => {
+      const error = new SeedlessOnboardingError('Test error', {
+        details: 'Additional context for debugging',
+      });
+
+      expect(error.message).toBe('Test error');
+      expect(error.details).toBe('Additional context for debugging');
+      expect(error.cause).toBeUndefined();
+    });
+
+    it('creates an error with an Error instance as cause', () => {
+      const originalError = new Error('Original error');
+      const error = new SeedlessOnboardingError('Wrapped error', {
+        cause: originalError,
+      });
+
+      expect(error.message).toBe('Wrapped error');
+      expect(error.cause).toBe(originalError);
+    });
+
+    it('creates an error with a string as cause', () => {
+      const error = new SeedlessOnboardingError('Test error', {
+        cause: 'String cause message',
+      });
+
+      expect(error.cause).toBeInstanceOf(Error);
+      expect(error.cause?.message).toBe('String cause message');
+    });
+
+    it('creates an error with an object as cause (JSON serializable)', () => {
+      const causeObject = { code: 500, reason: 'Internal error' };
+      const error = new SeedlessOnboardingError('Test error', {
+        cause: causeObject,
+      });
+
+      expect(error.cause).toBeInstanceOf(Error);
+      expect(error.cause?.message).toBe(JSON.stringify(causeObject));
+    });
+
+    it('handles circular object as cause by using fallback message', () => {
+      const circularObject: Record<string, unknown> = { name: 'circular' };
+      circularObject.self = circularObject;
+
+      const error = new SeedlessOnboardingError('Test error', {
+        cause: circularObject,
+      });
+
+      expect(error.cause).toBeInstanceOf(Error);
+      expect(error.cause?.message).toBe('Unknown error');
+    });
+
+    it('creates an error with both details and cause', () => {
+      const originalError = new Error('Original');
+      const error = new SeedlessOnboardingError('Test error', {
+        details: 'Some details',
+        cause: originalError,
+      });
+
+      expect(error.message).toBe('Test error');
+      expect(error.details).toBe('Some details');
+      expect(error.cause).toBe(originalError);
+    });
+  });
+
+  describe('toJSON', () => {
+    it('serializes error with all properties', () => {
+      const originalError = new Error('Original error');
+      const error = new SeedlessOnboardingError('Test error', {
+        details: 'Debug info',
+        cause: originalError,
+      });
+
+      const json = error.toJSON();
+
+      expect(json.name).toBe('SeedlessOnboardingControllerError');
+      expect(json.message).toBe('Test error');
+      expect(json.details).toBe('Debug info');
+      expect(json.cause).toStrictEqual({
+        name: 'Error',
+        message: 'Original error',
+      });
+      expect(json.stack).toBeDefined();
+    });
+
+    it('serializes error without optional properties', () => {
+      const error = new SeedlessOnboardingError('Simple error');
+
+      const json = error.toJSON();
+
+      expect(json.name).toBe('SeedlessOnboardingControllerError');
+      expect(json.message).toBe('Simple error');
+      expect(json.details).toBeUndefined();
+      expect(json.cause).toBeUndefined();
+      expect(json.stack).toBeDefined();
+    });
+
+    it('serializes error with custom error type as cause', () => {
+      class CustomError extends Error {
+        constructor() {
+          super('Custom error message');
+          this.name = 'CustomError';
+        }
+      }
+      const customError = new CustomError();
+      const error = new SeedlessOnboardingError('Wrapper', {
+        cause: customError,
+      });
+
+      const json = error.toJSON();
+
+      expect(json.cause).toStrictEqual({
+        name: 'CustomError',
+        message: 'Custom error message',
+      });
+    });
+  });
+
+  describe('inheritance', () => {
+    it('is an instance of Error', () => {
+      const error = new SeedlessOnboardingError('Test');
+
+      expect(error).toBeInstanceOf(Error);
+      expect(error).toBeInstanceOf(SeedlessOnboardingError);
+    });
+
+    it('has a proper stack trace', () => {
+      const error = new SeedlessOnboardingError('Test');
+
+      expect(error.stack).toBeDefined();
+      expect(error.stack).toContain('SeedlessOnboardingError');
+    });
+  });
+});
diff --git a/packages/seedless-onboarding-controller/src/errors.ts b/packages/seedless-onboarding-controller/src/errors.ts
index 7f5c0224de8..8a6916ad05b 100644
--- a/packages/seedless-onboarding-controller/src/errors.ts
+++ b/packages/seedless-onboarding-controller/src/errors.ts
@@ -135,3 +135,75 @@ export class RecoveryError extends Error {
     return new RecoveryError(errorMessage, recoveryErrorData);
   }
 }
+
+/**
+ * Generic error class for SeedlessOnboardingController operations.
+ *
+ * Use this when you need to wrap an underlying error with additional context,
+ * or when none of the more specific error classes (PasswordSyncError, RecoveryError) apply.
+ *
+ * @example
+ * ```typescript
+ * throw new SeedlessOnboardingError(
+ *   SeedlessOnboardingControllerErrorMessage.FailedToEncryptAndStoreSecretData,
+ *   { details: 'Encryption failed during backup', cause: originalError }
+ * );
+ * ```
+ */
+export class SeedlessOnboardingError extends Error {
+  /**
+   * Additional context about the error beyond the message.
+   * Use this for human-readable details that help with debugging.
+   */
+  public details: string | undefined;
+
+  /**
+   * The underlying error that caused this error.
+   */
+  public cause: Error | undefined;
+
+  constructor(
+    message: string | SeedlessOnboardingControllerErrorMessage,
+    options?: { details?: string; cause?: unknown },
+  ) {
+    super(message);
+    this.name = 'SeedlessOnboardingControllerError';
+    this.details = options?.details;
+    if (options?.cause) {
+      if (options.cause instanceof Error) {
+        this.cause = options.cause;
+      } else {
+        let causeMessage: string;
+        if (typeof options.cause === 'string') {
+          causeMessage = options.cause;
+        } else {
+          try {
+            causeMessage = JSON.stringify(options.cause);
+          } catch {
+            causeMessage = 'Unknown error';
+          }
+        }
+        this.cause = new Error(causeMessage);
+      }
+    }
+  }
+
+  /**
+   * Serializes the error for logging/transmission.
+   * Ensures custom properties are included in JSON output.
+   *
+   * @returns A JSON-serializable representation of the error.
+   */
+  toJSON(): Record<string, unknown> {
+    return {
+      name: this.name,
+      message: this.message,
+      details: this.details,
+      cause:
+        this.cause instanceof Error
+          ? { name: this.cause.name, message: this.cause.message }
+          : this.cause,
+      stack: this.stack,
+    };
+  }
+}
diff --git a/packages/seedless-onboarding-controller/src/index.ts b/packages/seedless-onboarding-controller/src/index.ts
index 4d445795530..1cdde0d2a84 100644
--- a/packages/seedless-onboarding-controller/src/index.ts
+++ b/packages/seedless-onboarding-controller/src/index.ts
@@ -22,4 +22,4 @@ export {
   SecretType,
 } from './constants';
 export { SecretMetadata } from './SecretMetadata';
-export { RecoveryError } from './errors';
+export { RecoveryError, SeedlessOnboardingError } from './errors';