The Welsh side had dropped down to fifth as they waited until Sunday to play their round-three fixture but showed little sign of nerves as they scored nine tries to win with ease.
Ospreys had eight different try scorers among their number, with Rhys Webb grabbing two to emerge as the star man, while Dan Biggar scored 16 points thanks to his unerring form with the boot.
By contrast, defending champions Leinster's indifferent start to the new season continued as they slipped to their second defeat of the season in losing 10-9 away to Connacht.
Matt O'Connor's men looked to be back on track after recovering from a loss to Glasgow Warriors to beat Scarlets in week two, but came up second best yet again at Galway Sportsground.
Kieran Marmion's second-half try did the damage for the hosts, who moved up to third place after preserving their winning record.
Glasgow Warriors also got a third victory in as many matches under their belt as they posted a convincing triumph away at Newport on Saturday.
The Warriors were reduced to 14 men just 40 seconds after half-time as Tyrone Holmes was dismissed for an apparent stamp on T Rhys Thomas.
But that had little impact on the outcome for Gregor Townsend's men, who ran in four tries to pick up a bonus point in a 33-13 win.
Ulster were also comfortable in beating Cardiff Blues 26-9 at Cardiff Arms Park, a result that sees them move into fourth.
Elsewhere, Munster ensured Zebre remain winless as they earned their first home victory of the season.
Simon Zebo picked up a hat-trick of tries to help Anthony Foley's men earn a 31-5 success over their Italian opposition.
But Zebre were kept off the bottom of the league by Benetton Treviso, who suffered a 43-0 thrashing at the hands of Scarlets in Llanelli.
Gareth Davies and Liam Williams ran in two tries apiece to see the Welsh side claim a bonus point.