The Gophers (23-14) will face Stanford in the championship game Thursday. The Cardinal beat Massachusetts 74-64 in Thursday's other semifinal game.
Hollins scored all seven of the Gophers' points in overtime.
Rodney Williams had 18 points and 10 rebounds for Minnesota and Austin Hollins had a dozen, including two 3-pointers.
Terrance Ross scored 21 for Washington (24-11) and Darnell Grant had 12 points and 10 boards.
Washington trailed 38-26 at halftime but went on a 12-4 run in the final 2 1/2 minutes of the second half to tie the score and force overtime.