The car, which had already made its track debut in a disrupted run at Misano last week, features a completely new livery for 2017.
Toro Rosso has used a largely unchanged design since it joined Formula 1 in 2006, but this season will sport a striking blue and red livery - the colours of Red Bull's Simply Cola brand.
Apart from a new look, Toro Rosso will also use a new engine this year, the Faenza-based squad returning to Renault power units after running year-old Ferrari engines in 2016.
The STR12, designed by a technical team led by James Key, incorporates a 'shark fin' that most cars will sport this year.
The car will be driven by Carlos Sainz Jr and Daniil Kvyat, the Spaniard in his third season at Toro Rosso.
Kvyat rejoined the team after losing his Red Bull seat to Max Verstappen from the Spanish Grand Prix onwards last year, and secured a contract extension for 2017 late in the season.
Toro Rosso will join its rivals on-track for the first day of pre-season testing at Barcelona on Monday.