It was the third straight victory for Virginia (3-3, 2-0 Atlantic Coast Conference). The Cavaliers trailed 9-3 late in the third quarter before scoring 10 points in a 19-second span.
After Robert Randolph kicked a 31-yard field goal, linebacker Darren Childs deflected a pass by Maryland quarterback Chris Turner. The 290-pound Collins latched onto the ball, broke to his left and took it down the sideline into the end zone.
Maryland's Nick Ferrara missed field goal tries of 44 and 37 yards in the fourth quarter. Then, after Turner threw an incomplete on a fourth-and-17 from the Maryland 2, Rashawn Jackson scored for Virginia with 1:43 left.
The Terrapins (2-5, 1-2) have lost four of five.
Maryland fumbled four times, losing two, and Turner was intercepted twice.
Virginia played the fourth quarter without quarterback Jameel Sewell, who left with an undisclosed injury. The Cavaliers finished with 67 yards rushing, the first time in 16 games since 1957 that Virginia beat Maryland when rushing for fewer than 100 yards.
After Ferrara kicked a 29-yard field goal to make it 9-3 with 6:08 left in the third quarter, a fluky reception by Virginia's Kris Burd set up Randolph's second field goal. Burd was on his back near the sideline when Antoine Perez dropped a potential interception, and the ball landed on Burd's chest for a 28-yard gain.
Then Collins gave the Cavaliers the lead for good. It was the third interception returned for a touchdown against Maryland this season.
The Terrapins finished with a minus-3 turnover differential and are minus-13 for the season.
Maryland led 6-3 at halftime after holding the Cavaliers to 12 yards on 15 plays in the second quarter.
The Terrapins' first drive ended with a fumble by David Meggett at the Virginia 24, setting the tone for the afternoon.
On their second possession, the Cavaliers had a first-and-goal at the Maryland 1 but had to settle for a 32-yard field goal. The Terrapins tied it when linebacker Adrian Moten forced a fumble by Sewell at the Virginia 33 and Ferrara followed with a 48-yard field goal.
An attempted rugby punt by the Cavaliers' Jimmy Howell went for minus-3 yards and went out of bounds at the Virginia 40, setting up a 30-yard field goal.