The 20-year-old from Oxford is currently contesting the Moto2 series with the team and will stay put next year alongside Belgian rider Xavier Simeon.
"We are in no doubt that in 2012 he can be a genuine title contender before he makes the step to MotoGP," team manager Herve Poncharal said of Smith, who was runner-up in the 125cc world championship in 2009.
"One more year in Moto2 will help him gain more valuable experience, so that when he moves to our MotoGP Team in 2013, he will be immediately competitive."
Smith himself said: "To think I'll be riding a Yamaha 1000cc MotoGP bike just over a year from now is hard to believe.
"I've worked so hard for many years to earn the chance to be given an opportunity like this, and now it has come I intend to grab it with both hands."
Tech3 currently field Cal Crutchlow in motorbike racing's premier category alongside American Colin Edwards. Crutchlow is the only British rider currently racing in MotoGP.
Edwards, however, is moving to the new NGM Forward Racing team, who are expected to use a Yamaha engine and Tech3 chassis in MotoGP next season.