The former England captain and double-Lion toured South America with the Baa-Baas in 1998 and has accepted an invitation to play again on the 2009 tour that features a ground-breaking game against Australia in Sydney on 6 June as well as the annual date with England.
He said, "The Barbarians' tour to Argentina and Uruguay was a fantastic experience and this year's trip promises to be equally memorable. I've played for England against the Baa-Baas so I know what a great occasion these games at Twickenham can be.
"I feel privileged to be involved again because the Barbarians' tradition and approach remains unique. I am absolutely thrilled at the prospect on putting on that black-and-white jersey again and running out at a ground that means so much to me."
The Barbarians will assemble a 23-man squad for the two games on tour including three members of the team that beat South Africa at Twickenham in 2007 - Rocky Elsom (Leinster & Australia) and the All Blacks Jerry Collins (Toulon) and Justin Marshall (Saracens).
French back-rower Serge Betsen (London Wasps) has also accepted an invitation to play.
David Young, who has guided Cardiff Blues to the quarter-finals of the Heineken Cup and the final of the EDF Energy Cup this season, reprises his role of last summer as Barbarians' coach. Mike Catt of London Irish will be assistant coach on this year's tour.