Career
Born and raised in Zambia, Mumbi started his career at local club Tazara Express in Kapiri Mposhi before relocating to the United States, playing college soccer for Stratford Academy. After two years he returned to Zambia, joining and winning the Zambian Premier League title in his second season with the club In 2005, Mumbi returned to the United States to compete in the USL Premier Development League playing for Ajax Orlando Prospects, the farm team of Dutch club Ajax Amsterdam.
He made five league appearances while scoring twice in one season with Ajax, before returning to Zambia and joining Lusaka Dynamos.
Playing in the Zambian Premier League once more, Mumbi remained with the Dynamos for one season, before joining crosstown rivals City of Lusaka. In 2008, Mumbi joined Petro do Huambo competing in the Girabola, the top flight of football in Angola.
After one season he returned to Zambia, playing for Zamsure for six months. He then joined Dolo Mando in India for six months, before returning to Angola to join Progresso.
Mumbi has played for Zambia at various youth levels.
He has also played for the senior team on several occasions, playing in the Africa Cup of Nations qualifying matches against Botswana and Rwanda.