Yes, in many cases you can start a business while working for another employer. However, your ability to do so may depend on your employment agreement, company policies, the type of business you plan to start, and any legal obligations that apply.
Before launching your business, it is important to understand whether your new venture could conflict with your duties to your employer or violate any contractual or workplace requirements. Issues commonly arise when an employee competes with the employer, uses employer time or resources, solicits the employer's customers or employees, uses confidential or proprietary information, or pursues business opportunities that belong to the employer.