Collins's appointment as the next Bishop of Dorchester, the area bishop for the whole county of Oxfordshire outside the cathedral city itself, was announced in November 2020. Due to the COVID-19 pandemic, his consecration as a bishop was postponed from 28 January, and instead he was licensed as episcopal vicar for the area "ad interim"; a role more common in the Roman Catholic Church and almost unique in the Church of England. His consecration was planned for 12 April, but because of the death of Prince Philip, Duke of Edinburgh that weekend, the service was held privately at Lambeth Palace on 14 April 2021 with a limited congregation under COVID restrictions, and it was not live-streamed. He was consecrated a bishop by Sarah Mullally, Bishop of London, in a service which began at 9:45am.