London Welsh captain Jonathan Mills and front row forward Arthur Joly have agreed new two-year deals with the club.
Mills, 28, joined the Exiles in 2007 from the Scarlets and last season led Welsh to Championship success and promotion to the Aviva Premiership for the first time in the club's history.
The back row/second-row forward has made 162 appearances for Welsh, scoring 12 tries, and was man of the match in the first leg of the Exiles' Championship final victory over the Cornish Pirates at Mennaye Field.
Mills, who took over the London Welsh captaincy at the start of the 2010/11 season, came through the academy at Bath and has also played for Llanelli RFC and Llandovery. He represented Wales at U16, U18, U19 and U21.
Prop forward Joly, 24, has made 12 appearances for London Welsh since joining the club from Bourgoin.
He represented France at Under U20 level in the Six Nations and was selected for the 2007 IRB Under-19 World Championships in 2007 in Belfast.
"I want to stay at London Welsh for as long as I can" said Mills.
"I've been here for a long time already and I look forward to more success in the future.
"To see the club where it is now, its vision for the future and the calibre of players we have is fantastic. We now want to really establish ourselves in the Aviva Premiership - that's the next challenge.
"Having first come to London Welsh on loan when the club was still semi-professional and to then be part of it going full-time professional, reaching two Championship semi-finals and then finally getting promoted and reaching the Premiership has been hugely satisfying.
"At the beginning of the season people said we wouldn't get a point, but the work-rate and the hunger of the boys has been tremendous. It's been fantastic to be a part of that."