It was the sixth victory in a row for the Terrapins (13-1), who have won their conference opener in all three seasons since joining the Big Ten. It was Maryland's largest conference-opening win since an 89-60 victory over Clemson on Jan. 5, 1974.
Malcolm Hill had 21 points for the Illini (10-4), who saw their six-game winning streak come to an end.
Their absences mattered little against the Illini, who never led and were outscored 48-24 in the paint. It also provided an opportunity for Maryland graduate transfer L.G. Gill, who matched a season-high with seven rebounds.
After both teams struggled with turnovers in the early moments, Maryland uncorked a 10-0 run to seize a 15-4 lead. The Terps' lead would never shrink below nine points as the Illini failed to get traction on offense. Maryland held a 39-23 edge at the break.
The Terps were 55.9 percent from the field while Illinois, which dropped its Big Ten opener for the fourth time in five years, shot just 35.6.
Maryland will host Nebraska on Jan. 1 at noon at XFINITY Center next time out.