He died on 4 November 2018, as the Archbishop Emeritus of Mombasa, Kenya, one month shy of his 90th birthday.
He was born on 25 December 1928 to Peter Kimani and Maria Wanjiru in Tigoni, Kiambu County, Kenya.
He studied both philosophy and theology at a seminary at Kibosho, Kilimanjaro Region in Tanzania, before he was ordained a priest in 1957.
On 1 April 2005, the age-related application for retirement from pastoral services submitted by Archbishop John Joseph Njenga, was accepted by the Holy See.
While there, he continued to serve the Church through Archbishop Njenga Foundation, a charitable Organization for the vulnerable children.