In December 1960 Kibaki left the lecturing job to join the Kenya African National Union (KANU) as the Executive Officer.

Kibaki was influenced by former Cabinet Minister Tom Mboya to quit his lecturing job and join KANU, a party he had helped to craft its constitution. Tom Mboya and Kibaki were Mang’u alumni, they were both bright and staunch catholics.
Initially Mboya had wanted Kibaki to join Nairobi Peoples Convention Party (PCP) as they waited for the registration of Kanu. After they had done the paper work in June 1960, Tom Mboya handed them for registration with Kenyatta as the President. The registrar refused to register Kanu as long as Jomo Kenyatta was the president and as long as trade unions formed part of the membership.

Later, Mboya invited Kibaki to become a member of Kenya Education Trust which was to coordinate the second airlift of students to United State of America (USA). Kibaki, and Dr. Munyua Waiyaki became the new faces of the airlift.

On the day that Kanu won election, a photo of Tom Mboya and Kibaki jumping and hugging captured their deep-rooted friendship. Both would together help to draft the famous sessional paper No. 10 on African socialism and its application to development that spelt out the pace which Kenya’s economy would take.

As an Executive Officer Mwai Kibaki was critical in the setting up of the party structures that aided in making it a formidable vehicle to take up the country’s leadership.  He was also part of the team tasked with writing Kenya’s first constitution. The constitution was instrumental in offering the first set of laws that would govern an independent Kenya in 1963.