Lucy Kibaki was born Lucy Muthoni in 1940 to the Rev. John Kagai, a pastor of the Presbyterian Church of East Africa and Rose Nyachomba, in Mukurwe-ini, Mount Kenya. She was educated at Alliance Girls High School, then trained as a teacher, working first at Kamwenja Teachers College and later at Kambui College in Kiambu, where she rose to the post of principal.
She met Mwai Kibaki in 1960. After a two-year romance, the couple married in 1962, with Lucy quitting her teaching career in 1963. They had four children: Judy Wanjiku, Jimmy Kibaki, David Kagai, and Tony Githinji. Kibaki was a patron of the Kenya Girl Guides Association.
Lucy died on April 26, 2016, at Bupa Cromwell Hospital in London, after brief hospitalization at the Nairobi Hospital for chest pains.
She can be remembered for her no nonsense character when the husband was the President. Being the first lady, Lucy managed to slap four men: Matere Keriri, Gitobu Imanyara and Clifford Derrick