Taken over by the Royal Fleet Auxiliary in 1970. She first saw combat in the Falklands War of 1982, when along with all the Royal Navy's other amphibious shipping, it was sent to recapture the Falkland Islands from an Argentine occupation force. The ship suffered slight damage on 24 May whilst lying in San Carlos Water, when an Argentine Skyhawk dropped a bomb that glanced off the ship.The ship deployed to the Persian Gulf in 1991 in support of Operation Granby.
In 1994, the ship was modernised in a service life extension programme to give it 15 more years of service life. The ship was lengthened by 12 metres, had its superstructure altered to a more modern design, the engines and bow thruster were replaced.
After returning to service in 1998, the ship was sent to Sierra Leone in 2000. Its most recent deployment was in support of Operation Telic in 2003, where the ship operated as the command vessel for the British and American mine countermeasures ships. Sir Bedivere left the UK in September 2002 for the Mediterranean, and operation Argonaut 2002. It was then diverted to the Persian Gulf accompanied by four British minesweepers. In 2006 Sir Bedivere returned from Sierra Leone and its part in operation Vela. Although originally intended to serve until 2011, Sir Bedivere was decommissioned on 18 February 2008. By December 2008 Sir Bedivere had been sold to Brazil, joining her sister ship ex-Sir Galahad. She was handed over to the Brazilian Navy on 21 May 2009 at Falmouth.