Cittadella won the first promotion play-off, beating Brescia 1-0, and will now face Monza in the semi-final.
Kick-off was delayed by 29 minutes due to technical problems with VAR, which was being used for the first time in this Serie B season.
As Cittadella finished higher up the table than Brescia, sixth compared to seventh, they would be guaranteed passage to the next round if the tie was level after 90 minutes and extra time.
That wasn’t necessary, as a twisting Federico Proia header on Marco Rosafio’s cross just before half-time proved decisive.
Cittadella will now play Monza home and away on May 17 and 20 in the promotion play-off semi-finals.
This evening, Venezia and Chievo go head-to-head, aiming to earn the right to face Venezia in their semi-final.
The Final will be played over two legs on May 23 and 27 to see who joins Empoli and Salernitana in Serie A next season.
Cittadella 1-0 Brescia
Proia 40 (C)