In 2002 when it was listed on the JSE Security Exchange, African Rainbow Minerals joined with Harmony Gold Mining Ltd. and the company's name changed to ARMgold. Motsepe is also the founder of African Rainbow Minerals Platinum (Proprietary) Limited and ARM Consortium Limited, which later equally split ownership with Anglo American Platinum Corp Ltd. From 2005, Motsepe was Chairman of Teal Exploration and Mining Incorporated. Motsepe is also chairman of Ubuntu-Botho Investments, Non-Executive chairman of Harmony Gold Mining Co Ltd. and deputy Chairman of Sanlam Ltd. Motsepe has been president of South Africa's Chamber of Commerce and Industry.
Motsepe won South Africa's Best Entrepreneur Award in 2002. In 2004, he was voted 39th among the South African Broadcasting Corporation's Great South Africans. In 2008, he was reported as the 503rd-richest person in the world, according to the Forbes 2019 list of The World's Billionaires, then ranked as the 962nd-wealthiest person in the world, and the third-wealthiest South African for 2019. In 2020, Motsepe was ranked as the 1,307th-wealthiest person in the world by Forbes, with a reported fortune of US$2.1 billion.