Evan Cummins scored 12 points, Weisner Perez grabbed 13 rebounds and Agunwa Okolie had 10 boards for the Crimson (8-8), who outrebounded Ryerson 58-32.
Ryerson, of Toronto, Ontario, Canada, led early, but Perez hit a go-ahead jumper amid a 10-2 run for the Crimson. Miller hit two 3-pointers during a 13-3 spurt and Harvard led 38-23 at halftime.
The Rams traded baskets with the Crimson in the second half, but failed to gain ground. Patrick Steeves' layup with 3:16 to go put Harvard up 69-52 and the Rams got no closer than 15 the rest of the way.
Jean-Victor Mukama and Aaron Best scored 12 apiece for the Rams, who play in the Ontario University Athletics league.
Harvard will conclude non-conference play on Saturday, Jan. 16 at Howard.