The game ended 75-7 with doubles from Jonathan Spratt and Sam Davies, while Aisea Natoga scooped up the man-of-the-match with a try-scoring display of his own.
It leaves the Welsh region third in the table and four points ahead of Glasgow Warriors, who enjoyed success away from home at Cardiff Blues on Saturday night.
Gregor Townsend's men did it the hard way however, clawing back a ten-point deficit in the second half as a last-gasp Mark Bennett score took the spoils at Arms Park.
Connacht fans saw their team win for just the third time in the RaboDirect PRO12 this season after Pat Lam's men battled to an 11-7 victory against Edinburgh at the Sportsground.
Craig Ronaldson endured a wayward evening from the tee but in response to Roddy Grant's first half try, Michael Swift burrowed over the try-line while Dan Parks' penalty gave them enough breathing space to cling on.
On Friday, Leinster were handed a fright by Newport Gwent Dragons but their pack power eventually told with two penalty tries in a 31-19 victory.
Dragons rustled up two quickfire scores through Richie Rees and Ashley Smith shortly after the interval but the Irish province bit back to record their fifth win in their last six RaboDirect PRO12 games.
They are hot on the heels of leaders Munster, who gave Zebre short shrift in a comfortable 36-8 win on Saturday night.
Simon Zebo proved he is back to his scintillating best after recent trouble with injury to touch down twice - and make sure Munster finished Round 14 three points clear at the top of the RaboDirect PRO12.
TRY OF THE WEEKEND
Mark Bennett stole the headlines with his winning try at the death, but Lee Jones' best impression of a bowling ball set the wheels in motion on the stroke of half time for Glasgow Warriors.
Jones, who joined on loan from Edinburgh a fortnight ago, deflected a series of desperate tackles starting from just outside the Blues' 22 to storm his way through to the whitewash.
BREAK OF THE WEEKEND
After running Treviso ragged all day, it is fair to say Ospreys had worn the Italians down by the time Matthew Morgan appeared off the bench to rub salt into the wounds.
And the fly-half did so in ruthless style, cutting Treviso lines to ribbons deep into his own half before offloading to Sam Davies for the simplest of tries.
PLAY OF THE WEEKEND
Leinster may have fought back on Friday night but opportunistic turnovers nearly paved the way for a Dragons shock.
The Welsh region dotted down twice after hawking the ball at the breakdown in the space of five minutes, hooker Rhys Thomas in particular showing impressive anticipation to spark Richie Rees' try.
PLAYER OF THE WEEKEND
Cian Healy is still the main man at loosehead for Leinster but with Jack McGrath's emergence he could soon be looking over his shoulder after a titanic display from the youngster.
Destructive scrummaging - after an equally pulverizing try in the first half - steadied the ship for Leinster in a performance that suggests the 24-year-old's future is very bright indeed.
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