Thierry Henry was in the stadium to see his investment in Como pay off when the Italian second-tier club won promotion to Serie A. (More Football News)
Como, coached by Henry's former Arsenal teammate Cesc Fabregas, drew with Cosenza 1-1 on Friday to clinch second place in Serie B and end a 21-year absence from the top tier. Leader Parma already sealed promotion.
Como could replace Frosinone in Serie A after the latter lost to Serie A champion Inter Milan 5-0.
With two weeks of the season remaining, six teams are still hoping to avoid joining Salernitana in the second tier.
Frosinone is 16th on the 20-team table, two points above the relegation zone. It has two games left, while teams above and below it have three. The result ended Frosinone's six-game unbeaten run.
Davide Frattesi scored Inter's first-half opener and Marko Arnautovic made it 2-0 after an hour. Canadian midfielder Tajon Buchanan got the third with his first goal for the club.
Lautaro Martinez's left-foot shot was his 24th goal of the league. Marcus Thuram completed the rout with a nice lob.