Venezia will have a team back in Serie A for the first time in 20 years after Venezia won a promotion play-off on Thursday.
A 1-1 draw with Cittadella was enough for a 2-1 aggregate win despite playing most of the tie with 10 men.
Venezia join Empoli and Salernitana, who were automatically promoted from Serie B, in the top flight next season.
Riccardo Bocalon scored in the third minute of injury time after Federico Proia had given Cittadella the lead in the 25th minute.
Cittadella, bidding to reach Serie A for the first time, were unable to take advantage of Venezia being reduced to 10 men in the 36th minute when defender Pasquale Mazzocchi was red carded.
Empoli, Salernitana and Venezia will replace relegated Benevento, Crotone and Parma in the top flight.