Mallot picked up the puck in the neutral zone afterAshton Sautner hit him with a clearing pass before the Moose winger skated down the left side and snapped a wrister past Mads Sogaard, beating him with a low shot.
The goal was his 13th of the season.
Ashton Sautner had a goal and an assist for the Moose.
Simon Lundmark had the other goal.
Oskari Salminen made 18 saves for Manitoba, who moved to 14-7-2-1 on the season and took four points from the Senators in their two-game series this weekend.
Egor Sokolov had a goal and an assist for Belleville.
Mathew Wedman also scored for the Senators.
Mads Sogaard turned aside 23 shots for the Senators, who dropped to 11-14-1-0.
Ashton Sautner scored 12:03 into the first when Nicloas Jones fed him a pass at the left point which the Moose defenceman stepped into, beating Mads Sogaard just inside the left post with a slap shot to give Manitoba a 1-0 lead.
The goal was his first of the season.
Egor Sokolov tied the game 10:58 into the second, scoring on a wraparound to make it 1-1.
The goal was his 7th of the season.
Mathew Wedman gave the Senators the lead 16:23 into the second when he knocked a rebound off an Egor Sokolov shot past Salminen mid-air to make it 2-1 Belleville.
Simon Lundmark tied it 8:51 into the third when Greg Meireles got possession of the puck behind the Belleville net and moved toward the corner before hitting Lundmark with a soft pass from the goal line.
Lundmark beat Sogaard glove side with a high shot to knot the contest at 2.
The goal was his 2nd of the season.
The game went to overtime where Sokolov almost ended it just over a minute into the extra frame when he grazed the goal post with a wrister from the hash mark.