Kirima was appointed the Roman Catholic Bishop of Mombasa in February 1978.[1] He was appointed as Bishop of Niyeri in 1988 to replace the late Bishop Caesar Gatimu.[1]
Archbishop Kirima underwent a kidney transplant in 2002 when his brother donated one of his kidneys to him.[1] His health remained good until 2006 when Kirima developed kidney failure while on a trip to the United States.[1] His health continued to deteriorate over the next year. He lapsed into a coma on November 4, 2007, while visiting Consolata Mission Hospital-Mathari, where he was receiving kidney dialysis.[1] He was airlifted to Nairobi Hospital for treatment but did not recover.[1]
Archbishop Nicodemus Kirima died at Nairobi Hospital in Nairobi, Kenya, on November 27, 2007, of kidney complications.[1] He was 71 years old.