It was just the ninth career NHL appearance for the 22-year-old, who appears to have elbowed Jonas Gustavsson out of a job for the time being.
Clarke MacArthur, Darryl Boyce and Kris Versteeg scored for Toronto (21-25-5), which shut out a team for the first time this season.
Coach Ron Wilson said before the game it was an easy decision to start Reimer because he's been solid every time he's played.
Reimer denied Chad LaRose on a breakaway in the second period and made 12 saves in the final 20 minutes as a desperate Carolina team tried to climb back into the game.
Carolina fell to 25-21-6 - remaining one point behind eighth-place Atlanta in the Eastern Conference standings.
There were a couple of occasions where Reimer's teammates bailed him out.
The most notable effort came from checking-line forward Tim Brent, who blocked three shots during a 5-on-3 penalty kill that lasted 1 minute, 36 seconds in the second period. It was a hooking penalty to Reimer that put the Leafs down two men.
During another penalty kill later in the period, Luke Schenn swept the puck off the goal line after Sergei Samsonov got a shot behind the Toronto goalie.
The Leafs took a 2-0 lead after the second period.
MacArthur's 16th goal of the season - one off his career high - came on a long wrist shot that seemed to fool a screened Cam Ward. The Hurricanes' goalie didn't have much chance when Boyce blocked a Joni Pitkanen clearing attempt along the boards and raced to the middle before beating him at 14:52.
Versteeg made it 3-0 at 6:25, just moments after Ward made one of the best saves of the season. He dove across the net to take a likely goal away from Brent.
The loss was the second in a row for the Hurricanes coming out of the All-Star break, leaving them in ninth in the Eastern Conference. Carolina returns home to face the Thrashers on Saturday.
Notes: Toronto has been shutout eight times this season. ... Gustavsson has made one appearance since Jan. 7. ... Carolina's Jussi Jokinen sat out with a lower-body injury. The Hurricanes have just 25 man games lost to injury this season. ... Tomas Kaberle has played 871 career games as a Leaf - 669 more than Nikolai Kulemin, the next highest among current players. ... Fergie Jenkins dropped the puck on the ceremonial faceoff.