Pelous, who won 118 Test caps for France over a 12-year period, will be joined by fellow new appointees Jake White and Carol Isherwood. White coached South Africa to World Cup glory in 2007, while Isherwood is a leading administrator in the women's game.
"I have enjoyed a wonderful career in rugby as a player and captain and joining the IRB rugby committee will give me a fantastic opportunity to pass on some of the knowledge I have gained," said Pelous, who retired from professional rugby at the end of last season.
"I look forward to working with the very talented professionals on the rugby committee and I am committed to ensuring our great game continues to grow and develop for future players at whatever level they play."
"The IRB is delighted that Fabien Pelous has accepted the IRB council's invitation to join the rugby committee," said Lapasset.
"Having retired from playing the game only this year, Fabien has considerable experience of the modern Test and domestic game environment and will give the committee a valuable insight into important issues such as player welfare and trends within the game."
As well as new additions Pelous, White and Isherwood, the IRB rugby committee comprises IRB council members Graham Mourie (chairman), Chris Le Fevre (Canada), Bill Nolan (Scotland), John O'Neill (Australia), David Pickering (Wales) and Pat Whelan (Ireland).