A second-half own goal from Federico Di Francesco and Francesco Tavano's subsequent strike saw Maurizio Sarri's men seal second place behind Palermo with a 2-0 win at home to Pescara.
The victory saw Empoli finish four points clear of third-placed Latina, meaning they will return to the top flight for the first time since 2007-08.
Tavano led the way for the promoted side with 22 league goals, while former Middlesbrough forward Massimo Maccarone – on loan from Sampdoria – netted 15 times.
With the four teams below them playing out draws on the final day of the regular season, the same result would have been enough for Empoli at their Stadio Carlo Castellani home.
But Di Francesco's embarrassing own goal 20 minutes from time meant Sarri's men could breathe easily.
The Pescara player tried to clear a cross with his left foot, only to miss and see the ball hit his right boot and go in.
Tavano completed the win and his standout campaign soon after as Empoli celebrated their return to Serie A.
Latina, Cesena, Modena, Crotone, Bari and Spezia are in the play-offs, aiming to be the third and final team promoted.
