The home side ran in seven tries while the previously unbeaten Irish visitors crossed four times in a high-scoring encounter on the highveld.
There were three tries in the opening 20 minutes of the game with Lions crossing twice through SJ Kotze and Eduan Keyter but Ulster responded with a try by Robert Baloucoune to make the score 14-7.
James Hume then got on the scoresheet for the Irish outfit before Baloucoune went over for his brace sandwiched between a Chris Smith penalty for the hosts.
The Lions though went up a gear and flank Ruan Venter crashed over for a five-pointer, with Smith adding the extras and a penalty to stretch the score to 27-19.
Baloucoune completed his hat-trick to close the gap on the scoreboard Renzo du Plessis secured the bonus-point try for the Lions.
Centre Henco van Wyk scored after a slick counter-attack and replacement prop Conrad van Vuuren crossed twice in the dying minutes to make the score look emphatic for the home team.
The tournament takes a month break after this weekend, with the Lions next taking on the Bulls at Loftus while Ulster travel to Benetton.
Daniel Smith's blistering knock helped Western Province overcome the North-West Dragons in their tournament opener at Newlands, while Boland notched their second consecutive win, edging the DP World Lions at the Wanderers.
The Sharks have announced that head coach John Plumtree will step down at the end of the 2025/26 season as part of a broader restructuring of the club's coaching and rugby operations.
Sharks head coach John Plumtree was pleased with his side's United Rugby Championship bonus-point victory over Scarlets, but acknowledged that his team is still a work in progress.
The Stormers, Lions and Sharks all picked up wins in another strong showing by the South African teams in Round 5 of the United Rugby Championship.
