Sibu has a Bachelor of Commerce in Law and an LLB from the University of Witwatersrand. Before being called to the Bar, Sibu volunteered at the Constitutional Court where she was part of the Constitutional Hill Education Project. She was later employed at Ombudsman for Short Term Insurance. Sibu has a general practice in commercial litigation, she also has an interest in Insurance, Public law and Family law. Sibu is also a part time lecturer at Wits University.