Heights (5-2) began the evening with a 61 power rating, fourth in Group 2. Eight teams will qualify.
Heights, which picked up 17 power-rating points with the win, will face Collingswood next week, the playoff cutoff.
"We're hoping to get a top-four seed and a first-round playoff game," Heights coach Ralph Schiavo said.
Sterling, which will face Overbrook at next week's cutoff, isn't in a great position but also isn't out of the running to earn its first playoff berth since 2005.
The two losses suffered by Haddon Heights were to West Deptford and Paulsboro by a total of 11 points.
West Deptford is the defending champion and, until further notice, the favorite, but Heights was competitive in the first game and should be if there is a rematch.
Senior Dante Pinckney is playing varsity quarterback full time for the first time after being a receiver, and he has enjoyed a smooth transition. Pinckney was a quarterback growing up, and he is as dangerous with his arm as with his legs.
He completed 17 of 26 passes for 162 yards and a touchdown, a 5-yard strike to Connor McCoy.
"Our passing and running game has worked well, and a lot of our credit goes to the offensive line," Pinckney said.
Sterling was trailing by 23-14, but driving with a first down on the Heights 14 when Garnets linebacker Kenneth Lewis ended the drive with an interception with 9 minutes, 27 seconds left.
Pinckney and McCoy then had interceptions on Sterling's final two drives.
As much as Heights likes to throw the ball, the Garnets ran it much more in the second half and were highly effective.
Two of their running backs, Brandon Smith (ankle) and Brandon Joyner (knee), didn't play because of injuries. Senior Khyleef Moore gained 119 yards on 18 carries.
"We had to dig down deeply for this one," Schiavo said.
The Garnets, as quick as they are, had trouble with Sterling receiver Gerald Crismond, who had six receptions for 74 yards and a touchdown, but the Silver Knights were hurt by interceptions and penalties.
On defense, Heights is so quick converging on the ball. Teams appear to have big gains, which suddenly close up.
It's just another reason that nobody will be too happy when paired against Heights when the postseason begins in two weeks.
Haddon Heights 7 7 9 0 – 23
Sterling 7 7 0 0 – 14
S: Gerald Crismond 20 pass from Marcus Taylor (Taylor kick)
H: Connor McCoy 5 pass from Dante Pinckney (Ian Lynch kick)
H: Pinckney 1 run (Lynch kick)
S: Khalil Howard 26 run (Taylor kick)
H: Safety, ball snapped out of end zone
H: Julian Faison 4 run (Lynch kick)
Contact Marc Narducci at 856-779-3225, firstname.lastname@example.org or @sjnard on Twitter.