Lloyd, 19, is the youngest Wales senior international ever, having made his debut at the age of 17 years and 76 days in 2010, and has made four appearances for the Warriors first team.
Broncos coach Tony Rea said: “We just wanted to make sure we had enough numbers; we’ve had a number lot of injuries so we wanted to make sure we were covered.
“We’re delighted give Rhodri an opportunity, we’ve heard really good things and he’s played with a few of our guys previously at the Crusaders. They spoke highly of him and we’re looking forward to some good footy from him.”
London will be Lloyd’s fourth club of 2013 – he has made six appearances on dual-registration with South Wales, three for Leigh on a similar basis, and one for Wigan.