Del Rio will undergo surgery Monday, McElwain said.
Making his first start of the season for the 21st-ranked Gators, Del Rio left the 38-24 win in the second quarter. He was slow to get up after rolling out of the pocket, completing a pass to Brandon Powell and getting knocked down.
Del Rio was favoring his left, nonthrowing shoulder as he walked off the field, and trainers looked at him on the bench. He then headed to the locker room for X-rays.
Feleipe Franks, who started Florida's first three games of the season and was benched in two of them, replaced Del Rio in the second quarter. Franks went on to complete 10 of 14 passes for 185 yards.
"It's hard when that stuff happens, when you get hurt like that," Franks said. "I can only imagine what he's going through, him and his family. It's emotional. I definitely wanted to keep him in my prayers, especially when I was out there on the field.
"You want to play for somebody, and that was one of the persons I wanted to play for because he's done nothing but support and helped me the whole time I've been here at Florida. It hurts."
The son of Oakland Raiders coach Jack Del Rio started six games last year before sustaining a season-ending injury to his right shoulder. Del Rio also partly tore the medial collateral ligament in his left knee. He had surgery on both shoulders after the season.
Del Rio was 16-for-25 for 138 yards with 1 touchdown and 1 interception this season.
The Associated Press contributed to this report.