Can I sue my employer for not paying my bonus?

Yes, you can sue an employer for not paying you your bonus if this was covered in your contract. Failure to pay an employee a bonus that is covered in their contract would be a breach of the employee contract. Because of this, you might be able to sue on the basis of breach of contract.

Now, not every contract includes bonuses. If that is the case, then you most likely do not have any reason for suing for a bonus. You are not entitled to a bonus unless it has been explicitly stated in a contract. There may be exceptions to this, such as if you have something else in writing that can hold up in court.