The win gave the Bulldogs a 2-0 lead in their second-round Ontario Hockey League playoff series and was Hamilton’s 16th consecutive win dating back to the regular season.
OHL defenceman of the year finalist Nathan Staios netted the winning goal 56 seconds into the third period with the Bulldogs on a 5-on-3 power-play.
Mason McTavish and Ryan Humphrey also scored for top-seeded Hamilton in front of 2,986 fans at FirstOntario Centre.
The Steelheads, who also lost Game 1 by a score of 4-2, got goals from Aidan Prueter and Luke Misa.
Game 3 will be held Tuesday night in Mississauga.
Hamilton Bulldogs vs. Mississauga Steelheads
Game 1, Thurs., May 5 at Hamilton – Bulldogs 4, Steelheads 2
Game 2, Sun., May 8 at Hamilton – Bulldogs 4, Steelheads 2
Game 3, Tues., May 10 at Mississauga, 7:00 p.m.
Game 4, Fri., May 13 at Mississauga, 7:00 p.m.
Game 5, Sun., May 15 at Hamilton, 2:00 p.m.*
Game 6, Tues., May 17 at Mississauga, 7:00 p.m.*
Game 7, Wed., May 18 at Hamilton, 7:00 p.m.*