He is a Presidential National Task Force member on the Kenya COVID-19 Emergency Response Fund and chair of its health committee.

Mwangi credits his mother for instilling the virtues of discipline, hard work, giving back to society, and humility from a tender age.

He attended Kagumo High School for his A-level education, where he studied economics, English literature, and geography.

He joined the University of Nairobi, graduating with a Bachelor of Commerce degree, after which he sat and passed the Certified Public Accountant of Kenya (CPAK) examinations.

After a short period at Price Water House, he moved over to Ernst and Young, where he worked for three years before joining Trade Bank.

Mwangi joined Equity Building Society as the Finance and Operations Director, a position he held until 2004 when he became the CEO.

Mwangi converted his KSh.7 million/= deposit at the time with Equity Building Society to ordinary shares, making him one of the key shareholders.

Additionally, he is on the Economic Advisory Board to the president of IFC (International Finance Corporation), the Advisory Network to the High-Level Panel for a Sustainable Ocean Economy, the Nairobi Advisory Board of Columbia Global Centres,[25] Yale University President’s Council on International Activities, the Inaugural Board of African Leadership Academy and has been chair of the steering committee of the Young African Leaders Initiative (YALI) Regional Leadership Center, East Africa.

[31][32][9] In 2010, under Mwangi's leadership, Equity Bank launched the Wings to Fly initiative, which provides scholarships to needy students in Kenya.

[33] His family’s notable contributions include US$4 million in donations to support the COVID-19 Response in Kenya, Rwanda, and DRC.