The 38-year-old Italian, who finished off a stellar career with three Major League Soccer seasons in Montreal, scored in the 27th minute only to see Fabian Espindola get the equalizer in the 86th as the Impact played to a 1-1 draw with D.C. United on Saturday.
"To finish my career is a little bit sad, but this has been a big day for me and my family, so I'm happy," said Di Vaio. "Scoring goals was my life, and this was the last time I will feel that emotion.
"But I received a lot of emotion from everyone in Montreal, inside and outside the stadium. I feel like a lucky guy."
The game meant nothing in the standings to either side.
Montreal (6-10-18) finished last in the 19-team MLS after a difficult season, although they took heart from going undefeated — three wins and three ties — in the last six home games.
D.C. United (17-8-9), which finished on a six-game unbeaten string, came first in the Eastern Conference and will face the winner of the fourth versus fifth place knockout game in the playoffs.
It poured cold rain throughout the match, but the crowd of 15,242 were there mostly to celebrate the career of perhaps the best player ever to put on the Impact's blue, white and black uniform.
The goal, scored on a solo run up the left side with a low shot slotted past goalkeeper Bill Hamid, was like many of the 34 he scored in 76 games for Montreal.
When he went in, Di Vaio performed his signature goal celebration — he kissed the ring on his left hand and lifted his arm to the sky.
"What I said to the group before the game is that I'm honoured to be part of this group and to finish my career here in Montreal," he said. "Every victory, every goal with this team is part of my memories. It was an incredible experience."
He was feted in a pre-game ceremony in which he brought his daughters Sofia, 8, and Sara, 6, onto the field, where he was presented with a painting of himself kissing his ring that was done by teammate Issey Nakajima-Farran, a professional artist when not playing soccer.
"This painting will come with me to Italy in my house," said Di Vaio, who is expected to take a job with his former team, Bologna FC, which was recently bought by a group that includes Impact president Joey Saputo.
Nakajima-Farran said the painting, which took 27 hours to complete, was called Taking Off The tape, a reference to the tape Di Vaio put over the ring during games.
"He's never going to take that tape off again," said Nakajima-Farran. "We had all the guys sign the back, so it was a collective thing.
"All the players wanted to be part of it, so I think it's a very personal present for him. He looked pretty happy. I was hoping he would cry, but he didn't."
Di Vaio joined Montreal three months into its MLS expansion season in 2012 after a long career in Italy as the team's first designated player. He quickly became it's most popular and productive player.
His 20 goals in 2013, none of them from the penalty spot, helped the Impact reach the playoffs in only its second MLS campaign.
A three-game suspension and some early injury trouble limited him to nine goals this season.
Nakajima-Farran said the Impact players were looking to set up Di Vaio in his last game.
It worked when Dilly Duka sent him in alone to score. Another chance in the 52nd minute was foiled by Sean Franklin's sliding clearance. Di Vaio had one last chance in added time, but chipped a shot just wide before he was substituted off to a standing ovation.
"It was a special moment," said Nakajima-Farran. "We were fighting to get possession of the ball, but we were always looking across to Marco.
"It was an emotional time for him."
Espindola got the equalizer when he cut across the edge of the penalty area from the right side and made a sharp turn and fired a low shot to catch Evan Bush leaning the wrong way.
Former Impact and Italy defender Alessandro Nesta, who had his own retirement game a year ago, was in attendance and was among a group of former teammates who saluted Di Vaio in Italian in scoreboard messages played at the intermission.
NOTES: Montreal used a makeshift back-line with Matteo Ferrari, Hassoun Camara and Heath Pearce all serving one-game suspensions. Academy products Karl Ouimette, Wandrille Lefevre and Maxim Tissot all started on defence. Midfielder Felipe Martins sat out with an injury. . . Former Impact captain Davy Arnaud did not dress for D.C.