Anthony Cowan led the Terrapins (1-0) with 15 points and Kevin Huerter added 13. Justin Jackson had a double-double with 10 points and a career-high 14 rebounds, helping Maryland to a 42-26 rebounding advantage.
The Terrapins started one of their largest lineups with the 6-7 Jackson and Huerter, 7-1 Michal Cekovosky and 6-9 Ivan Bender.
The Seawolves (0-1), who have only two players on their roster over 6-7, got 17 points from senior Tyrell Sturdivant, an All-America East selection last year. Maryland led by as many as 20 points, but Stony Brook closed to 69-57 with 4:06 to play on a 3-pointer by Akowaski Yeboah, who had 15 points.
Freshman Bruno Fernando was the fifth Terrapins player in double digits with 10 points.
The Terrapins led 41-23 at the half after jumping out to 17-8 lead in the first 10:19. Cekovsky, who finished with 10 points, scored six points in the early run.
Maryland later ran off 12 straight points to lead 31-13 with 5:12 left in the half on a Jackson free throw.
The two teams played the first college basketball game in newly renovated Nassau Coliseum.
Maryland, coming off a third straight NCAA Tournament appearance, improved to 4-0 all time against Stony Brook, which has made six straight postseason trips, including last year's CBI.
The Seawolves open this season with four of their first six games against teams that played in the postseason a year ago.