Wambui is from Nairobi, Kenya and is the National Treasurer of the Kenya Medical Practitioners Pharmacists' and Dentists Union (KMPPDU), which is a trade union dedicated to reforming the health sector in Kenya through advocacy exposing corruption, industrial action, and lobbying. KMPPU has helped to increase the salaries of thousands of doctors in Kenya, and has contributed to the reduction of graft across the healthcare system. Wambui is also currently a Medical Officer with the Kenyan Ministry of Medical Services. She holds a Bachelor degrees in Medicine and Surgery from the University of Nairobi.