The 6-foot-9 senior jumped out to a quick start, tying his season-high game total of 20 points by halftime. The Fighting Irish led 42-34 at the break.
Niagara (5-7) committed 11 fouls in the first half and the Irish (12-1) took advantage, hitting 12 of 14 (86 percent) free throws. Cooley made half of those and was perfect from the stripe.
The Irish got rolling as the game wore on, shooting a season-high 62 percent in their 10th consecutive victory. They put the game away with a 23-7 run during a 7-minute span midway through the second half, extending their lead to 20.
Antoine Mason led the Purple Eagles with 17 points.
It was Cooley's eighth double-double in his last 10 games. He entered tied for second nationally in that statistic.
A series of plays in the first half epitomized the night. Cooley's easy putback off a missed 3-point attempt from the corner by Eric Atkins gave the Irish a 36-26 lead with 3:09 to play. The next time down the floor, Cooley blocked a shot, grabbed the loose ball and then drew a frustration foul from Mason.
Cooley sank both double-bonus free throws, putting the Irish up 12.
Cooley, whose minutes were limited by the lopsided margin, fell three points and three rebounds shy of his career highs.
Freshman forward Cameron Biedscheid had 15 points for Notre Dame, shooting 4 of 4 from 3-point range.
The winning streak is the longest for the Irish since a 10-game run four years ago.
The Purple Eagles, who hadn't played a team ranked as high as No. 22 since 2000, fell to 12-78 against ranked opponents.
Niagara was able to keep the game close for the first 12 minutes, cutting Notre Dame's lead to 25-24 when Mason drove inside and hit a layup as he fell to the court. But Cooley answered with six straight points, making a pair of baskets inside and then two free throws. Pat Connaughton added a 3-pointer to cap the 9-0 run, giving the Irish a 34-24 lead.