Kingston and Osborne also staying on
Three senior members of Harlequins' management have committed their immediate future to the club.
The London club announced on Tuesday that Conor O'Shea, John Kingston and Collin Osborne, Director of Rugby, head coach and skills coach respectively, have extended their contracts with the club until the end of the 2015-16 season.
Given that Tony Diprose, first XV defence coach and Academy manager and Mark Mapletoft, backs coach, extended their contracts last year, the club will have a settled rugby management for the coming seasons.
This group of coaches have overseen the most successful period in the history of Harlequins in the professional era, winning four trophies in the past three seasons - the Challenge Cup in 2011, the Premiership title in 2012, and the A League and Anglo-Welsh Cup in 2013.
The same coaches have also been responsible for bringing through an exceptional group of talented, England qualified players from Academy to senior squad levels. Earlier this year, the club provided the captains of the England senior team (Chris Robshaw), the England Under-20 World Cup-winning team (Jack Clifford) and the England Under-18 team (James Chisholm).
Announcing the contract extensions, David Ellis, Chief Executive of Harlequins, said, "We are delighted to have retained the services of the coaching team that has delivered the most successful period in the professional history of this great club.
“Their extensive experience of managing players at the top end of the game in this country has been fundamental to Harlequins' recent progress; I am confident that will continue given the quality of young English talent we have coming through our player development programme."
Commenting on his contract extension with the club, O'Shea said, "I am very privileged to be asked to continue as Director of Rugby at Harlequins and would like to thank the club's owners and the Board for this opportunity.
“Every day I go into the club I meet a group of coaches, players and support staff that wants to be the best they can be and wants to bring success to a club that belongs at the top of the game.
"We are ambitious to ensure that what we are building here is a lasting legacy, that we play rugby in a style that our supporters enjoy and is true to the tradition of this club, a club that will celebrate its 150th anniversary in 2016," O'Shea concluded.