On 2 July 2015, it was announced that Tomlin would become Bishop of Kensington, an area bishop in the Diocese of London. On 23 September 2015, he was consecrated a bishop in Canterbury Cathedral by Justin Welby, the Archbishop of Canterbury. in 2017 he was involved in the aftermath of the Grenfell Tower fire in west London, and organised the national memorial service in St Paul's Cathedral in December 2017. He was the Vice Chair of the Archbishop of Canterbury's Commission on Housing, Church and Community.