Harlequins director of rugby Conor O'Shea, head coach John Kingston and skills coach Collin Osborne have extended their contracts with the club.
The trio will now remain at the Twickenham Stoop until 2016.
"We are ambitious to ensure what we are building here is a lasting legacy," the 43-year-old ex-Ireland full-back said.
"I am very privileged to be asked to continue 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."
Quins chief executive David Ellis said the coaching team had been "fundamental" to their progress as a club.
"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," Ellis said.
"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."