Ulster moved top of the United Rugby Championship with a fourth straight bonus-point win of the season but saw Will Addison taken off on a stretcher to dampen their victory over the Lions.
Full-back Addison was carried off in the 46th minute, having had his ankle trapped in a tackle.
The province had opened up a half-time lead with tries from Nick Timoney and James Hume.
Matty Rea and Timoney added further scores after the break to seal the win.
With Munster not playing until Saturday, Ulster leapfrogged their inter-provincial rivals into first with one more game, against Connacht at the Aviva Stadium next Saturday, to come before a month without a match as the autumn internationals take centre stage.
For a youthful team with many senior players still to come back, Ulster will be pleased to have successfully navigated the opening weeks of the season while securing maximum points.
But with stiffer challenges lying ahead, they will know more complete performances will be required if they are to remain at the top of the table in the months to come.
Addison's injury sucked the atmosphere out of Kingspan Stadium six minutes into the second half, with Dan McFarland revealing after the game that the full-back had been taken to hospital and that the injury "does not look great."
A fan favourite, Addison only made his return to action in April this year after 15 months out through injury.
Before then, he had not started back-to-back games since January 2020. Despite relentless injuries he has remained a huge influence at the northern province and went straight back into the international set-up for Ireland's summer games.
The extent of the injury suffered on Friday is not yet known, but the full-back immediately appeared in deep discomfort as members of the medical staff rushed to his aid before calling for the stretcher.
Ulster's mixed bag enough in early days of season
When the fixture list was released Ulster will have eyed their first four matches knowing that maximum points was really the expectation more than the hope, given they consisted of three home games and a trip to Zebre Parma.
The province have delivered on expectation, but have yet to hit top gear in terms of performance with all four games to date containing some bright, eye-catching moments amid displays lacking in any true rhythm.
Timoney's opening try from a smartly-worked line-out play in which the flanker collected Andy Warwick's offload after Rob Herring's low throw to the front got the scoreboard moving inside four minutes.
The Lions, the best South African team in the URC after the opening three rounds, used their sizable presence up front to get the better of the breakdown and work their way into the contest, scoring their first try on 17 minutes through Pienaar in the corner.
Chances came and went for Ulster, with Billy Burns missing a kick for touch and David McCann knocking on with the try-line at his mercy, as inaccuracy disrupted the host's search for momentum.
They did however find their rhythm towards the end of the half, keeping ball in hand and creating quick ball that brought them right to the Lions' line before Burns flung a pass wide for Hume to stroll in unchallenged.
After Addison's injury silenced the home crowd, Rea produced a power leg drive to soon provide a much-needed lift and bring the bonus-point in sight against a Lions side that did not threaten to overturn what was only a two-point half-time deficit.
It was Timoney, another who has impressed in the first rounds of the new season, who stepped up to find the fourth try minutes after Alan O'Connor had been held up just inches short of the line.
Ulster: Addison; Gilroy; Hume, Moore; McIlroy; Burns, Doak; Warwick, Herring, O'Toole; O'Connor, Carter (capt); Rea, Timoney, McCann.
Replacements: Roberts, O'Sullivan, Kane, Treadwell, Reidy, Shanhan, Lowry, Moxham.
Lions: Rossouw; Pienaar; Raas, Odendaal (capt); Maxwane; Viljoen, Warner; Sithole, Visagie, Sadie; Schoeman, Nothnagel; Sangweni, V Tshituka, Straeuli.
Replacements: Botha, Dreyer, Ntlabakanye, van der Sluys, E Tshituka, van den Berg, Zeilinga, Simelane.