The Ospreys flew into a 20-3 half-time lead thanks to Beck’s first touchdown and a rumbling effort from Paul James.
Beck got the scoreboard ticking again within minutes of the restart with his second try.
They were made to wait for the bonus-point as Treviso staged a mini revival with a Ludovico Nitoglia try but Joe Bearman and Tom Isaacs crossed the whitewash to seal maximum points.
The victory sees the Ospreys soar into second-place in the PRO12 table with just four regular league games left.
Fresh from their emphatic victory over league leaders Leinster last week, the Ospreys demonstrated plenty of early enterprise. Welsh record try scorer Williams gave a reminder of his mesmerising capabilities with some trademark darts, while Hanno Dirksen was also busy
Biggar booted the hosts into the lead on nine minutes after Corniel Van Zyl was caught offside in midfield before Burton quickly levelled the scores.
But the Ospreys fly-half produced a moment of aerial brilliance to create the game’s first try. He snatched his own up and under from the Treviso cover and released Dirksen down the right, who passed inside for Beck to score.
Biggar added the extras and stretched the hosts further in front with his second penalty.
The Ospreys continued to dominate affairs and they grabbed their second try thanks to the quick thinking of their triple Grand Slammer Jones, who ducked through a ruck.
The Wales prop ducked through and unselfishly fed front-row partner James, who rumbled over for a try awarded by the TMO. Biggar converted to bring the scores to 20-3 as half-time.
The Ospreys quickly resumed usual service with Williams at the fore and it was his miss-pass to that allowed Beck to grab his second.
Treviso hit-back with a Nitoglia try but it was Edoardo Gori that made the initial inroads with a sensational break.
Alberto Di Bernardo added the extras to hand his side a glimmer of hope at 27-10.
Tommaso Benvenuti was sent to the sin-bin on 70 minutes after deliberately slapping down Shane Williams’ pass and from the ensuing scrum Bearman rumbled over for the all-important bonus-point try.
But they saved the best for last as Williams went around Treviso’s defence before slipping to Beck.
The red-hot centre flicked a superb overhead pass to Isaacs, who finished brilliantly by stepping the last man.
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