Wambugu is the founder, director and the chief executive officer of Africa Harvest Biotech Foundation International (AHBFI) since 1994. AHBFI is a nonprofit foundation with offices in Nairobi, Kenya, Johannesburg, South Africa, and Washington, D.C. Previously, she founded, established and worked as Africa Region Director, ISAAA – Afri-center, in Nairobi. From 1978 to 1991, she worked as a senior research officer (pathologist) and coordinator of plant biotechnology research at the Kenya Agricultural Research Institute (KARI), Kenya. Thereafter (1991–1994), she was a post-doctoral fellow with Monsanto Company.