Sampdoria looked the better team from the first whistle, and they were rewarded for their efforts within 15 minutes, when Gabbiadini was played in behind and stabbed home his 65th all-time Serie A goal.
Luck would not remain on Sampdoria’s side however, as Monza reclaimed parity just past the half-hour mark. After collecting a pass deep inside the Sampdoria box, Andrea Petagna turned and rocketed a shot into the bottom corner to level the scoreline in style.
The second half produced similarly dramatic proceedings, and Sampdoria took advantage of the back and forth nature as the clock ticked up towards an hour.
After a superb team move, an initial Tomas Rincon effort was parried away, but Gabbiadini was on hand to tap home the rebound in front of the boisterous Sampdoria fans behind the goal, reclaiming the lead for the visitors.
While it looked for all the world that the visitors would hold on for a crucial victory, there was a twist in the tale when Monza were awarded a dramatic 97th minute penalty, after Petagna was taken down in the box.
In the face of the pressure, Pessina stepped up and dispatched the spot-kick to snatch a point with the last kick of the game.
Having got out of jail against a side they beat comfortably back in October, Monza will finish matchweek 21 in fine fettle.
They are now unbeaten in seven games, having also begun the night as just the second team in Serie A history to collect 25 points from the first 20 games of a debut top-flight season.
Flashscore Man of the Match: Manolo Gabbiadini (Sampdoria)