Shavlik Randolph added 18 points for the Blue Devils (11-1), who have won eight straight games and 34 in a row at home.
J.J. Redick scored 10 points, and hit his 48th consecutive free throw to tie the Atlantic Coast Conference record set by Jeff Lamp during the 1979-80 season.
With the victory, coach Mike Krzyzewski improves to 17-0 against his former assistant coaches and players. Stags coach Tim O'Toole, who was an assistant at Duke from 1995-97, has lost all three meetings with his mentor.
Deng Gai had 18 points and 11 rebounds for Fairfield (7-4), which has lost three straight. The Stags fell to 2-3 on their current 10-game road swing, which continues Thursday night at Elon.
Duke had a season-high scoring output and shot 53 percent against a team that had been allowing just 61 points per game. The Blue Devils also held the Stags to 38-percent shooting and forced 25 turnovers.
Duke took control with a 20-3 run midway through the first half, blowing open a close game with steady shooting and aggressive defense. Duhon fueled the Duke attack, finishing with 15 points, seven assists and four steals in the first half.
Duhon and the Blue Devils kept the pressure on after the break. In one three-play series, Duhon nailed a 3-pointer, had a dunk off a steal near midcourt and found Shelden Williams with a no-look pass for a 69-38 lead with 12:32 to play.
Duke shot 51 percent in the first half, including a 6-for-15 effort from 3-point range.
Fairfield had to work hard to get open shots as Blue Devil defenders chased Stags ballhandlers past the 3-point arc. Fairfield managed just two shots during Duke's big first-half run, going without a basket for more than five minutes and committing five turnovers.
The Blue Devils hit eight of 12 shots during their spurt, steadily building a double-digit lead. Duke ended the run with a 3-pointer from Deng and a three-point play from Duhon, taking a 40-21 lead with 5:44 left in the half.
The Stags got no closer than 14 points the rest of the way and trailed 52-31 at halftime.