 As a bishop, Warelwast attended the Council of Reims in 1119 along with three other bishops from England, as well as the Council of Rouen in 1118, a provincial synod for Normandy. In his diocese of Exeter he began the construction of a new cathedral in about 1114; it was consecrated in 1133. The existing two towers in the transepts date from that period. He also replaced the secular clergy staffing collegiate churches with regular canons: at Plympton in 1121 with canons from Aldgate in London, and in 1127 at the church in Launceston in Cornwall. In addition he founded a house of regular canons at Bodmin. Royal charters survive that granted several churches in Cornwall, Devon, and Exeter to Warelwast.
