Henson returns to Wales duty on Saturday after an absence of more than two years for an appointment with the Barbarians at what is likely to be a half-empty Millennium Stadium.
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 6 Nations campaign finale against Ireland, but he will now win his 32nd cap and have a chance to start pressing claims for World Cup squad selection later this summer.
And Gatland has made it abundantly clear that he expects Wales' centre of attention to seize the moment.
Gatland said: "It is an opportunity for players like Gavin to do his talking on the rugby pitch.
"We have Andrew Bishop, Jamie Roberts, Jonathan Davies and now Scott Williams, but we need depth, and hopefully Gavin does well and he puts some pressure on the established guys.
"He tells us it's fantastic to be back in this environment, that he has really missed it and he is loving his rugby at the moment, and that is a real positive for us.
"He knows he just needs to let his rugby do the talking now."
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.
Henson has never played in a World Cup, and Saturday's encounter starts Wales' pre-tournament schedule, which continues with August fixtures against England (twice) and Argentina.
Fly-half Stephen Jones will win his 100th cap, joining Gareth Thomas as Wales' second international centurion, lining up in a back division that also includes his fellow Scarlets Morgan Stoddart, George North and Jonathan Davies.
And there is also a start for scrum-half Mike Phillips, who has played a minimal amount of rugby since the Six Nations ended in March after the Ospreys agreed to let him leave them once he has found a new club.
Cardiff Blues flanker Sam Warburton captains a team that sees Newport Gwent Dragons number eight Toby Faletau, 21, and 22-year-old Ospreys prop Ryan Bevington make their Test debuts.
And there are three more uncapped players on bench duty in Dragons hooker Lloyd Burns, Blues prop Scott Andrews and Scarlets centre Scott Williams.
Faletau's fellow Dragons - wing Aled Brew and lock Luke Charteris - gain recalls, with Test back-row regular and former Wales skipper Ryan Jones starting in the second-row alongside Charteris, a position he has filled on a number of occasions for the Ospreys this term.
Gatland paid tribute to Stephen Jones, adding: "Stephen has reached a fantastic milestone and he deserves all the plaudits he will get.
"He still has so much more to give, and it is a testament to him that he is still hungry.
"He is not limping towards a century of caps with a sense of relief, but bursting through the landmark, relishing the Baa-Baas game but then intent on focusing on the World Cup and the matches ahead."
Gatland is without the services of several front-line players, including Six Nations skipper Matthew Rees, wing Shane Williams, full-back Lee Byrne, centres Jamie Roberts and James Hook, plus prop Adam Jones.
And the Barbarians line-up, which will be announced tomorrow, is likely to include Wales international forwards Martyn Williams and Iestyn Thomas.
"We have tried to get the right mixture of youth and experience in there, and I would like to think the likes of Ryan Bevington and Toby Faletau will look at this and think it is a good chance for them," said Gatland.
"You only have to look at the quality and the experience in the Barbarians squad to know that we are looking at a huge challenge this weekend.
"It's a psychological challenge that we need to be prepared for.
"There is a lot at stake for all of us, and for the players in particular in terms of us assessing their character and them booking their places on that plane for the Rugby World Cup."
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