Career
Mthembu began his youth career playing for local sides Fast Movers and Mvuzane Blue Aces prior to joining the Kaizer Chiefs academy. He only spent one year at Chiefs before he was suspended for suspected age cheating. He then moved to Vodacom League side Young Mates Football Club before joining Platinum Stars on a three-year deal in June 2012 after impressing in the 2012 Cape Town International Challenge.
He made his debut for Dikwena on 27 October 2012 in a 4–0 over Free State Stars at Royal Bafokeng Stadium, coming on, in the 85th minute.
He joined Supersport United in July 2014, as a free agent as his contract was not renewed, after he went for trials. He made his league debut for Matsatsantsa on 9 August 2014 in a 1–0 loss to Bidvest Wits, coming in as a substitute and played 18 minutes.
Mthembu has played for the South African under-20 team and was the top scorer with 5 goals at the 2012 Cape Town International Challenge. He was part of the South Africa squad for the 2013 COSAFA Cup and made his senior debut against Zambia on his 19th birthday.