Sundin, who also assisted on Alexei Ponikarovsky's tying power-play goal in the second period, hit the 20-goal mark for the 16th straight season - every one spent in the NHL. That was enough to give the Leafs their fifth win in six games, including four on the road.
Brendan Shanahan scored for New York, which had a two-game winning streak broken. The Rangers and Maple Leafs entered tied for ninth in the Eastern Conference, but Toronto - which had a vocal band of supporters in the stands - jumped into a three-way deadlock for seventh.
Andrew Raycroft, in his 13th straight start, made 37 saves as Toronto improved to 2-0 on its five-game trip one night after winning at Carolina. Shanahan nearly tied it with under five minutes left, but Raycroft stopped him at the left post.
New York's hopes of getting even were dashed when Matt Cullen took a holding penalty with 1:25 left.
Sundin made the biggest play of the night, taking a long feed from defenceman Ian White after a blocked shot in the Leafs zone. The Toronto captain came in alone on Henrik Lundqvist, his Olympic gold-medal winning teammate from last year's Turin Games, and snapped a shot into the top right corner at 6:32.
Lundqvist was sharp again in making 26 saves. He allowed nine goals in seven games, but is 3-4 in that span.
He helped keep his team in it when the Maple Leafs had three power-play chances in the first period. Toronto mustered only seven shots overall in the scoreless frame.
It was the Rangers who struck first, converting 12 seconds after Hal Gill was sent off for cross-checking Jason Krog in the Maple Leafs zone.
New York gained control of the puck and Shanahan fired a shot from the right circle. The puck rebounded to defenceman Karel Rachunek, who quickly slid it across to Jaromir Jagr for a drive. Shanahan, stationed in front, deflected the shot in with his left skate - drawing an immediate protest from Raycroft.
The play was reviewed and Shanahan's team-leading 26th goal stood up at 12:07 of the second. It gave him goals in consecutive games for the first time since Dec. 1-9 when he connected in three straight.
Rachunek was 24 seconds into a boarding penalty when Ponikarovsky scored his 16th goal while attempting a pass.
Ponikarovsky spotted Bryan McCabe darting toward the right post when he slid the puck through the crease, but instead of finding its mark it ricocheted past goalie Lundqvist off the right skate of defenceman Aaron Ward at 13:34.
The goal served as payback for Ponikarovsky, who earlier in the period was flattened by Ward's hard shoulder check. Ponikarovsky stayed down on his stomach, holding his head, for several minutes before gingerly making his way back to the bench.
Notes: Rangers C Ryan Hollweg, without a point this season despite playing in the first 50 games, was benched. ... New York D Michal Rozsival sat out after spraining a knee Monday at Boston. ... Sundin has 697 assists and 1,213 points in 1,201 NHL games. ... Rangers C Petr Prucha, who entered with 18 penalty minutes this season, earned six on three separate infractions.