France picked uncapped Brau-Boirie at centre to face Wales
The 20-year-old will start in the French midfield alongside his Pau teammate Emilien Gailleton, 22, after Bordeaux-Begles pair Nicolas Depoortere and Yoram Moefana were ruled out through injury.
The rest of the starting XV for Sunday's match is identical to the one that thumped Ireland 36-14 in France's tournament opener last week.
Galthie had hinted at pairing the Pau centres against Wales when he played them together with the rest of the starters in training on Tuesday, as Depoortere and Moefana sat out.
"It's true that it helps save time in terms of interplay when it's a pair of centres who already play together," France's attack coach Patrick Arlettaz had said on Tuesday.
"However, it's the national team, you have to deserve to play," he added. "It's better to have the best players on the pitch" regardless of which clubs they play for.
Arlettaz compared Brau-Boirie to former France great Yannick Jauzion, adding that "he has that kind of talent... to be understated and very effective, to make others around him play well".
He also praised Gailleton for his recent form amongst "a whole host of centres with enormous potential".
Amongst the replacements, Stade Francais centre Noah Nene is also in line to make his international bow as he replaces the injured Kalvin Gourgues.
Maxime Lamothe comes in for Peato Mauvaka as the replacement hooker and lock Thibaud Flament, who missed the Ireland match to accompany his wife in her fertility treatment, replaces Hugo Auradou on the bench.
Wales and France have beaten each other 51 times each in their 105 previous Test matches, with three draws.
But reigning champions France are on a seven-match winning run in the fixture and have scored more than 40 points in each of the last three, including last season's 43-0 drubbing in Paris.
Team (15-1)
Thomas Ramos; Theo Attissogbe, Emilien Gailleton, Fabian Brau-Boirie, Louis Bielle-Biarrey; Matthieu Jalibert, Antoine Dupont (capt); Anthony Jelonch, Oscar Jegou, Francois Cros; Mickael Guillard, Charles Ollivon; Dorian Aldegheri, Julien Marchand, Jean-Baptiste Gros
Replacements: Maxime Lamothe, Rodrigue Neti, Regis Montagne, Thibaud Flament, Emmanuel Meafou, Lenni Nouchi, Baptiste Serin, Noah Nene