Two goals in the space of five first-half minutes ensured the visitors had a comfortable half-time lead.
Scott Sinclair opened the scoring from the penalty spot, before Aaron Collins doubled the lead after a brilliant performance from the former down the right wing.
Luca Hoole closed out the points with less than a quarter hour to go when he headed in from a corner.
Karl Robinson made three changes to the squad that suffered a 1-0 defeat at Cambridge United last weekend as Stuart Findlay, Marcus Browne and Yanic Wildschut were restored to the starting line-up in place of Josh Murphy, Brandon Fleming and Tyler Smith. .
In Findlay’s case, it was the centre-back’s first start since the Boxing Day loss to Ipswich Town.
Despite trailing by two goals at half-time, United made a promising start to the game in the early stages.
Within 60 seconds, a floating corner from the left side came off a Rovers man and hit the post, with Ciaron Brown unable to shake off an away defender to land a death touch.
Five minutes later, Kyle Joseph shot wide from inside the penalty area.
Yanic Wildschut did well on the left and crossed to Joseph, who sent a first-rate effort down the wrong side of the woodwork.
With a quarter of an hour played, the U’s recycled a corner with Lewis Bate clipping the ball over the top for Sam Baldock, but the striker couldn’t stretch far enough and his toe-in was an easy catch for James Belshaw.
Two minutes later, Wildschut slid to the inside of the field and won a free kick at a central position from 35 yards out.
Marcus Browne stepped up and took the set piece, but sent it high and into the parking lot.
After 20 minutes, United lost Baldock to injury when Gatlin O’Donkor came on in his place.
Moments later, referee Charles Breakspear awarded a penalty to Rovers following Cameron Brannagan’s foul on Lamare Bogarde inside the box.
Sinclair stepped up and sent Eastwood the wrong way from 12 yards out with a confident right-footed shot.
Five minutes later, Joey Barton’s team doubled their lead.
Sinclair swooped down the right wing and laid the ball on a layup for Collins, who cleverly shot inside Simon Eastwood’s near post.
Rovers then did well to control play and keep the U’s at arm’s length, holding on to their two goal lead as the teams went to half time.
At the interval, Robinson made his second substitution as he retired Wildschut with James Henry taking his place.
The U’s got off to a bright start in the second period when O’Donkor played down the left channel, however Belshaw came quickly off his line to close the angle and the ball did not fall kindly to Henry in the six-yard box. .
As the ball fell to Browne on the edge of the box, his half-volley was sent comfortably over the crossbar.
Browne then sliced a ball through a gap on the Rovers back line, however, Joseph hauled his shot wide from the edge of the box, as he tried to divert the attention of an away defender.
Brannagan hit a 30-yard free kick against the wall, after Browne’s sprinting run resulted in Jarell Quansah taking down the U man.
With an hour on the clock, Henry fired a cross from the right, which Joseph failed to connect correctly and sent his header wide of the post.
Henry then saw space to run and shoot, and fired a low effort towards goal, but it was easy for Belshaw into the center of the Rovers goal.
Then a looping cross from Sam Long threatened to embarrass Belshaw as he got caught in the breeze and fell towards goal.
The Rovers goalkeeper, however, got a good look at the ball and claimed it under the bar.
With just over 20 minutes to go, Robinson’s final roll of the dice saw him bring on Tyler Goodrham and Ateef Konate in place of Lewis Bate and Browne.
A dangerous low corner nearly caused a calamitous moment for Henry when he cleared the ball at the near post but sent the ball across the woodwork.
Rovers added their third goal from a corner on the same side when Hoole rose higher in the box to head in from a set piece.
Oxford United (4-2-3-1): Eastwood; Largo, Moore, Findlay, Brown; Brannagan, Bat (Goodrham 68); Jose, Browne (Konate 68), Wildschut (Henry 46); Baldock (O’Donkor 20).
Unused Subs: McGinty, Fleming, Smyth.
Reserved: Bat.
Bristol Rovers (4-3-3): Belshaw; Hoole, Quansah, Gibson (Gibbons 76), Gordon; Finley, Coutts (70th Ward), Bogarde (70th Evans); Sinclair (Anderson 76), Marquis (Coburn 70), Collins.
Unused substitutes: Balcombe, Connolly.
Reserved: Collins, Quansah.
Referee: Charles Breakspear (Surrey)
Attendance: 8,437 (visitors to be confirmed)