Garrity made three 3-pointers and added six assists for the Hornets (11-10, 6-7 Big Sky), who came in with three one-point losses in conference play, including Monday's 62-61 heartbreaker to Northern Arizona.
Collin Chiverton had 12 points off the bench for the Eagles (6-17, 4-9).
Sacramento State led for most of the game, but Eastern Washington pulled ahead midway through the second half and led 48-44 after Thomas Reuter's 3-pointer with 8:43 to play. Sacramento State scored the next 10 points, capped by Mikh McKinney's two free throws with 4:15 left, to take the lead for good.
The Hornets led by as many as eight points in the first half before the Eagles closed the gap to 29-27 at halftime.
DouDou Gueye, a 6-foot-10 center from Senegal, has signed with Ball State as a graduate transfer from South Carolina State.
Duke freshman point guard Derryck Thornton Jr. is transferring to USC, his father announced on Friday to Scout.com.
We have changes at the top of the draft and a shakeup in the lottery, with teams starting to make their final decisions. Get the latest in Chad Ford's Mock Draft 9.0.