[1][3] Pope John Paul II appointed him Coadjutor Bishop of the Roman Catholic Diocese of Tunduru–Masasi on 7 December 2004.
He was consecrated and installed at the Diocesan Cathedral at Tunduru, in the Diocese of Tunduru-Masasi on 30 January 2005.
[1][3] For approximately two years before his death, Bishop Msemwa developed health issues for which he received medical care both inside and outside Tanzania.
On Wednesday, 18 October 2017 he left Tanzania and travelled to India to seek medical evaluation and treatment.
The next day, Thursday, 19 October 2017 he died in Muscat, Oman, while in transit to India to seek medical treatment.