The Demons (9-11 overall, 5-4 in the Southland) shot 54 percent overall, 88 percent at the free throw line and scored 31 points off 20 turnovers by the Wildcats (7-15, 1-7).
Northwestern, eighth nationally in steals per game (averaging 9.2), had 13 swipes, four by DeQuan Hicks and three each from White and West.
West scored 13 points and for the second straight game had 10 assists.
He entered the game 13th in the NCAA rankings with a 6.2 average, and also enhanced his No. 9-ranked steals average of 2.58 per game.
Freshman Zeek Woodley added 12 points for Northwestern, which got scoring from 12 of the 15 players who got into the game.
Parker Wentz and Rafael Farley each scored 18 for ACU, while James Pegues added 12.
The Wildcats managed to shoot just 38 percent overall, the second straight NSU foe held under 40 percent.
The Demons ran off the game's first 15 points, 13 by White, in a fierce opening 2:35-long blitz.
“We needed these two games,” White said. “I needed to step and be a leader. I needed to set the tone tonight and I just thank my teammates for getting steals and getting in the passing lanes.”
The Wildcats, whose top two scorers are sidelined, briefly fought back to as close as three points, 30-27.
They averted a blowout by sinking a season-high 12 3-pointers in 23 tries, making nine of 13 in the first half.
After seeing its lead nearly eroded, Northwestern scored the next six in row and settled for a 42-35 advantage at the break as White already had 17 points.
He made all five of his second-half shots and finished 4-of-6 on 3-pointers while making four assists and three steals, matching his career bests in both categories.
NSU started the second half with a 15-8 burst in the first six minutes to open a 58-43 lead on a West 3-pointer with 14:03 remaining.
ACU briefly closed the gap to 13 points, but got no closer and trailed by 22, their biggest deficit, after eight unanswered Demon points made it 71-49 with 5:45 to go. The final margin was the smallest spread afterward.
Northwestern continues its four-game homestand next Thursday against McNeese State (7-14, 5-4), which whipped Oral Roberts 79-68 Saturday.
The Demons are at home for the last time this month next Saturday against Nicholls (10-8, 7-2).
“It’s a completly different ball game when you have McNeese coming,” NSU head coach Mike McConathy said. “They are like a wounded animal. They came back and fought back hard to get a win against Oral Roberts.”