She entered legal practice as an attorney in her hometown, Port Elizabeth, and joined the bench in June 2002, becoming the first woman ever to be appointed to the Eastern Cape Division of the High Court of South Africa.
[2] In 1982,[2] she matriculated at Kenneth Masekela High School in KwaThema, a township outside Springs in the former Transvaal, and she went on to the University of the North, where she completed a BProc in 1987.
In June 2015, the Judicial Service Commission announced that Mhlantla was one of four candidates who had been shortlisted for possible appointment to fill a permanent vacancy on the Constitutional Court.
[11][6] She was nominated to the position by the National Association for Democratic Lawyers, of which was a founding member, and she was viewed as "a safe choice on the constitutional interpretation front", given her record of moderate judgements.
[12] On 9 November 2015, President Jacob Zuma announced that he would appoint Mhlantla to the Constitutional Court bench, with effect from 1 December.