A member of the South West Africa People's Organization (SWAPO), Mbumba has headed several Namibian Government ministries: Agriculture, Water and Rural Development (1993–1996), Finance (1996–2003), Information and Broadcasting (2003–2005), Education (2005–2010) and Safety and Security (2010–2012).

He succeeded to the presidency upon the death of Hage Geingob in February 2024 and announced that he had no intention of running for election for a full term later in the year.

[6][7] Beginning in 1993, Mbumba served in the National Assembly of Namibia and government ministries including Agriculture, Water and Rural Development (1993–1996),[8] Finance (1996–2003), Information and Broadcasting (2003–2005), Education (2005–2010), and Safety and Security (2010–2012).

[13] He was sworn in about 15 hours after Geingob's death on 4 February 2024 by Chief Justice Peter Shivute at the State House in Windhoek and appointed Deputy Prime Minister Netumbo Nandi-Ndaitwah to be his successor as Vice President.

[18] This award is named after Namibia’s iconic desert plant, and this accolade is the highest national honor recognizing individuals who have made significant contributions to the country.