Holden will re-join London Wasps having previously spent four years at the club between 2005 and 2009 in various roles including assistant coach and forwards coach.
During his previous time with the club, he was part of the coaching team who won a number of trophies including the Heineken Cup and Premiership.
London Wasps Chief Executive Chris Thomas said: "At this point of the season, it was vital that we selected the right person to support Shaun Edwards and the technical staff to oversee the squad's remaining involvement in the Aviva Premiership and Amlin Challenge Cup. It is an added bonus that Leon is well respected by the players and staff. We have been through a quick but vigorous selection process and we are delighted that Leon has accepted and will re-join the club."