The 29-year-old, who is currently without a club after failing to secure a new contract with wealthy French club Toulon, starts at inside centre.
Henson has not represented Wales since the 2009 RBS Six Nations campaign finale against Ireland, but he will now win his 32nd cap and have a chance to start pressing a claim for World Cup squad selection later this summer.
Ex-Ospreys star Henson had brief stints with Saracens and Toulon this season, his first competitive rugby since entering a self-imposed exile of more than 18 months from the game following repeated injury setbacks.
Appearances on two celebrity television programmes though, including the BBC's Strictly Come Dancing, ensured he stayed in the media spotlight.
Wales coach Warren Gatland said: "It is an opportunity for players like Gavin to do his talking on the rugby pitch."
WALES TEAM (to play the Barbarians at the Millennium Stadium on Saturday, 2:30pm) Stoddart (Scarlets); North (Scarlets), Davies (Scarlets), Henson (unattached), Brew (Newport Gwent Dragons); S Jones (Scarlets), Phillips (Ospreys); Bevington (Ospreys), Bennett (Ospreys), James (Ospreys), R Jones (Ospreys), Charteris (Newport Gwent Dragons), Lydiate (Newport Gwent Dragons), Warburton (captain, Cardiff Blues), Faletau (Newport Gwent Dragons). Replacements: Burns (Newport Gwent Dragons), Andrews (Cardiff Blues), AW Jones (Ospreys), Turnbull (Scarlets), Knoyle (Scarlets), Priestland (Scarlets), Williams (Scarlets).