They came close to scoring a couple of times in the first 20 minutes and Will Tupou had a 67th-minute try scrubbed for a double movement.
Brent Tate dragged the lacklustre Cowboys back into the contest with a 70th-minute try set up by a good pass from five-eighth Ray Thompson.
Matt Bowen's conversion got the Cowboys back to within eight points, but despite some late pressure they couldn't cross the Bulldogs line again.
The match featured some rib-rattling hits, particularly from Bulldogs hitman Frank Pritchard.
Together with Joel Romelo he lifted up Tariq Sims inside the first five minutes, with Romelo placed on report for his involvement.
A second Bulldog, prop Sam Kasiano, was also put on report for kneeing Sims in the second half.
Reynolds squeezed between two players from dummy half in the 25th minute to score his third try of the season.
Winger Steve Turner's conversion hit the post and bounced away, but he kicked a 40th-minute penalty goal to give the Bulldogs a 6-0 halftime advantage.
Bulldogs fullback Ben Barba had a try go begging after a ball hit the post late in the first half and recalled centre Josh Morris had another potential four-pointer rubbed out for losing the ball over the Cowboys line in the 45th minute.
It wasn't costly as shortly after Reynolds broke the line and combined with halfback Trent Hodkinson to send Turner clear in the 48th minute.
Turner's conversion and 57th-minute penalty goal blew the Bulldogs buffer out to 14 points.
CANTERBURY 14 (J Reynolds S Turner tries S Turner 3 goals) bt NORTH QUEENSLAND 6 (B Tate try M Bowen goal) at ANZ Stadium. Referee: Jared Maxwell, Gavin Morris. Crowd: 8,654.
- AAP