The Blue Devils (8-0) steadily broke open the game in the second half after holding a 43-31 lead at the intermission.
Fellow freshman Sheldon Williams contributed 16 points and 10 rebounds for Duke, which improved to 163-8 against non-conference opponents at Cameron Indoor Stadium under Mike Krzyzewski.
Fairfield (5-5) had more turnovers (23) than baskets (22).
Oscar Garcia scored 19 points and Deng Gai added 12 for the Stags, who dropped to 0-2 all-time against the Blue Devils. Fairfield coach Tim O'Toole was an assistant under Krzyzewski in the mid-1990s.