The 20-year-old follows in the footsteps of another Leeds player, Ben Jones-Bishop, who had a sensational season-long loan spell at Quins in 2010.
Harlequins Acting Head Coach Rob Powell said: “We are grateful to Leeds for sending Luke down to join us for next season and we hope the relationship between the two clubs can continue.
“Luke is a talented, young player who is enthusiastic about coming down and starting training next week. He is a strong ball carrier who will add size to our pack and is a player keen to push for a first team place in 2011. I look forward to welcoming Luke and I am confident he will fit into London life straight away and be a valuable member of the squad.”
Leeds Rhinos Head Coach Brian McDermott added: “Leeds have always recognised that for some players it is better for their development to stay within our system, however, for others it is important that they go out and play with men. I think over the years, the club have realised that those players who go away to Quins come back better players and better people from the experience and that is certainly what we will be looking for from Luke.”
Halifax-born Ambler joined the Rhinos in 2008 from Salford City Reds on a two year contract. He began his playing career with his local amateur club Elland and gained representative honours for Yorkshire Under-17’s where he played alongside current Rhinos team mate Paul McShane.
Luke made his first appearance for the Rhinos in the Festive Challenge game against Wakefield and then was part of the pre season fixtures against Hunslet, Hull FC and his former club Salford in Florida.
A regular with the Reserve Academy in his first season he scored nine tries over the campaign. Luke was also given the opportunity to gain valuable first team experience whilst on loan with National One side York City Knights.
His form earned him a call up to Andy Kelly’s Ireland squad for the 2009 European Cup and made his debut in the 82-0 win over Serbia. He also played in the matches against Wales and Lebanon and was a first choice prop for Ireland in their 2010 Alitalia European Cup campaign where he was a teammate of Quins local boy, Jamie OCallaghan.