Bishop Rotich was born on July 27, 1957 at Tegat Village, Longisa in present day Bomet County. He joined St Augustine Major Seminary, Mabanga, from 1977 – 1979 for his philosophy training before joining St Thomas Aquinas Major Seminary, Langata, from 1979 – 1983 for Theology training.
He was ordained a priest of the Diocese of Nakuru on November 18, 1983 by the Archbishop Emeritus of Nairobi (then Bishop of Nakuru), Most Rev Ndingi Mwana a’ Nzeki. On March 9, 1996, he was appointed as Auxilliary Bishop of Nairobi and on the same date, he was appointed as Titular Bishop of Iulium Carnicum.
He was ordained as Titular Bishop of Iulium Carnicum on July 3, 1996 by then Archbishop of Nairobi, His Eminence Maurice Michael Cardinal Otunga.
On August 29, 1997, he was appointed Bishop of the Military Ordinariate and installed on November 1, 1997.
He was the first full-time bishop of the Military Ordinariate. He served as Military Chaplain. He rose through the ranks to become Captain from 1989 to 1993, a Major from 1994 to 1996, and further rose to become colonel, the highest rank that a religious person can rise in the military. Bishop Rotich has been living in Nairobi since his resignation and has been very active in the pastoral ministry of the Church, holding various positions at KCCB.
He has served as Bishop Chairman of Caritas Kenya and the Social Communications Commissions. He is currently the Bishop Chairman of the Commission for Ecumenism, Vice Chairman of the Commission for Inter-Religious Dialogue and also Vice Chairman of the Family Life National Office. He is a Bishop Member of the Catholic Justice and Peace Commission and the Mainstream Church Leader’s Forum.