Fry worked around a bit of wildness in the first. After two routine the ground balls, Fry hit Zac Mitchell and walked Matt Beaty before fanning Judah Akers to end the inning.
BU managed a two out single in the second off of Fry, but failed to reach base in the third.
The Beavers dealt with a two out threat in the fourth after Alec Diamond and Jared Breen both singled up the middle.
Designated hitter Phillip Parsley drove a pair of balls down both the left field and right field lines that caused a bit of commotion before they found foul territory.
"All of our players went to the top step to see where the ball landed," said Belmont head Coach David Jarvis of Parsley's shot to left. "I was saying a little prayer. That was the best thing that I could do.
"I have no idea how foul it was, but in my mind it was just inches foul."
On a full count with the runners in motion, Fry walked Parsley to load the bases after a barrage of foul balls.
"I am thrilled to death for Phillip," said Coach Jarvis. "He gave us a senior mentality in that batter's box."
Nine hole hitter William Dodd was unable to convert his opportunity and ended the inning with a lazy fall ball to right.
The Bruins did their best to pick up where they left off in their next at bat thanks in large part to an inning opening triple by leadoff hitter Dylan Craig.
"They always seem to have us in a two out hole," said Jarvis. "The exception was when Dylan led off the inning with a (triple). Our kids were able to execute and get the run home in that situation."
Craig sprinted home from third to tie the score at on Zac Mitchell's ground ball to short.
With the game knotted at 1-1, Fry experienced some pain his arm and eventually gave way to reliever Tony Bryant with nobody on and a 2-2 count in the top of 6.
"He said that he felt a little twinge in his arm," said Oregon State head coach Pat Casey. "With him being a freshman guy, we are going to protect him. We have a good bullpen, so we're going to protect him."
Fry ended the day allowing four hits and an earned run. The southpaw walked three and struck out four during five innings of work, but not factor in the decision.
Belmont starter Chase Brookshire was equally good as his Pac-12 counterpart.
After a 1, 2, 3 first inning, the Beavers were able to cash in a Ryan Barnes leadoff double that set the table for Kavin Keyes' sacrifice fly that gave Oregon State a 1-0 lead.
OSU found very little success in the middle innings against Brookshire who retired the Beavers in order in the fourth and fifth innings.
The Beavers were able to break the hex in the 6th with a Joey Matthews double to open the home half of the frame.
Tyler Smith's ground ball to the right side moved Matthews over to third with just one out.
Michael Conforto was intentionally walked to set up the double play, but a beautiful push bunt from Ryan Barnes rode the first base line all the way to the first base bag allowing all runners to advance and pushing Smith across the plate for the go ahead run giving OSU a 2-1 lead.
"I had taken a fastball down the middle on the first pitch," said Barnes with a chuckle. "On the second pitch, I sort of widened out to make sure I got my bunt down.
"The dirt stayed pretty true. Once it rolled off the grass, it just kept rolling."
Belmont did their best to answer in the top of the seventh. A two out single by Drew Turner chased Tony Bryant who was replaced by left hander Matt Boyd.
Boyd came in and was able to get Zac Mitchell to chase a 3-2 pitch that tailed inside to end the inning stranding Turner at second.
The Bruins' fortunes never improved against Boyd who went the rest of the way and recorded his third save in relief of winning pitcher Tony Bryant.
"I thought he was really good," said Coach Casey of Boyd. "He is a guy that we contemplated making a starter at the beginning of the year.
"It was important for us to get somebody in to keep them off the board. Boyd was really good. He had his fastball, breaking ball and his change. I thought his three pitch mix was really good."
With the win, the Beavers (39-19) move on to the winners' bracket game Saturday night at 5 p.m. PT.
Belmont (39-23) will take the field Saturday at 12 p.m. PT in an elimination game.