Martin Seiferth scored 12, Drew Bandon grabbed 10 rebounds and the Eagles (10-12, 5-6 Big Sky) shot 52.8 percent from the field and 52.4 percent (11 of 21) from 3-point range.
Calen Coleman opened with a layup for the Bobcats (10-12, 5-6), but it was all Eastern Washington after that. Jois sank two free throws, sparking a 13-2 run and a 17-6 Eagles lead. A 7-2 run boosted the lead to 28-13 and Eastern led 36-20 at halftime.
Eastern opened the second half with an 8-2 run, led 63-36 after a 9-1 run, and continued to pull away.
The Eagles won the rebound battle 38-22, and the Bobcats finished shooting 38.8 percent (19 of 49).
Coleman and Flavien Davis led Montana State with nine apiece.