Touchdowns from Ruan Combrinck (2), Stokkies Hanekom (2), Derick Minnie and Gavin Annandale sealed victory for the Lions, outscoring their visitors six tries to two.
The Johannesburg outfit is preparing for their promotion/relegation playoff fixture against the lowest ranked South African side in this year's Super Rugby competition in July.
WP called up the Stormers' trio of Scarra Ntubeni, scrumhalf Nic Groom and prop Chris Heiberg in their squad, so the players could earn some much needed game time.
Ntubeni has missed most of the season due to injury, and Groom has fallen out of favour with the Stormers' management following a string of disappointing performances.
The hosts got off to the best possible start when Combrinck was put through by the Lions backline, before dotting down inside the opening three minutes. Marnitz Boshoff added two points from the conversion.
Having gained the early advantage, the Lions had to wait 20 minutes before doubling their lead through Hanekom, before Boshoff converted, putting the home side 14 points ahead before the half-time break.
Hanekom scored his second of the night four minutes later, after a promising WP attack ended in Hanekom sprinting home from inside his own 22 metre area.
WP conceded their fourth try shortly after, as Combrinck went over for his second, which Boshoff coolly converted to keep his 100 percent record intact as the game approached the interval.
The visitors started where they had left off in the opening period, as Dillyn Leyds ran over for WP's second, which flyhalf Tim Swiel converted for his first successful attempt at goal.
WP maintained the pressure, but 11 minutes from time, the Lions stretched their lead to 23. Flank Derick Minnie waltzed past the WP defence and trotted over for the home side's fifth try under the posts.
Gavin Annandale was next to dot down for the Lions, after the second half replacement picked up a loose ball behind a ruck on the WP tryline and crashed over for five points shortly before the full-time whistle.
Lions coach Johan Ackermann believes a disappointing second-half performance against Western Province undid the ground work
"I think we started well, but then we lost track," Ackermann said.
"We started to make individual mistakes and we couldn't hold onto the ball.
"Our discipline let us down and it was actually a disappointing second half.
"Our defence wasn't as good as we needed it to be, but if you're going to give penalties away consistently, you're going to struggle."
The Lions stormed to a 28-0 lead inside half an hour, before Joshua Katzen restored some confidence in the visiting team's ranks.
Ackermann admitted the scoreline may have been somewhat complimentary toward the hosts.
"We couldn't say it was bad because there was some individual brilliance. We looked quite energised and we looked good in attack," he said.
"The Province team is a young side but full of talent, and they've tested us, and that is the kind of game we need. But if we look at ourselves, we weren't good."
Ackermann said his side would need to improve their discipline ahead of their match against the Sharks next week.
"Partially you can put it down to us making a lot of changes (to the team at half-time), but also it shows how important it is to play on a weekly basis," he said.
"Last week we were off and I think it was reflected in our performance.
"The signs were there that we weren't there for the game this evening."
Full time Lions 42 (28) Western Province 12 (5)
Tries: Ruan Combrinck (2), Stokkies Hanekom (2), Derick Minnie, Gavin Annandale
Conversions: Marnitz Boshoff (5), Lionel Cronje (1)
Tries: Joshua Katzen, Dillyn Leyds
Conversion: Tim Swiel