Joseph Mairura Okemwa (born 29 June 1954), is a Roman Catholic prelate in Kenya, who is the Bishop of the Roman Catholic Diocese of Kisii. He was appointed as bishop by John Paul II on 19 December 1994.
He was born on 29 June 1954 in Nyabururu Village in Kisii County in the Diocese of Kisii, in Kenya.
He was ordained a priest of Kisii Diocese on 27 October 1987. He worked in that role until 19 December 1994.
On 19 December 1994, Pope John Paul II appointed him bishop of the Roman Catholic Diocese of Kisii. He was consecrated as bishop on 21 July 1995. The Principal Consecrator was Cardinal Maurice Michael Otunga, Archbishop of Nairobi assisted by Archbishop Zacchaeus Okoth, Archbishop of Kisumu and Bishop John Njue, Bishop of Embu.