Mhlengi has an extensive legal background. After obtaining his degree, he worked as a legal researcher in Qatar. He then returned to South Africa and completed his articles with VBH Attorneys, after which he was retained by the firm for a year. During his time at VBH Attorneys, he worked at both the defended and undefended departments as well as being a trial attorney. He then worked as legal adviser to Beautistaff Enterprises, where his main responsibilities were contract negotiations and drafting as well as general legal advice for the entity.
He is currently part of the Litigation team at the firm where he handles motor vehicle recoveries and liability matters, commercial matters, contractual matters, public liability as well as personal injury matters .
Mhlengi is currently awaiting his admission as an attorney.