Stormers took control of the game with four tries in 16 second-half minutes, Evan Roos, Herschel Jantjies, Daniel du Plessis and Deon Fourie all going over
Clermont led for much of the first 45 minutes thanks to Anthony Belleau’s three penalties, but were undone following the fly-half’s yellow card, Bautista Delguy crossing for their solitary try.
It was a turgid first half at the DHL Stadium, with neither side able sustain any meaningful pressure – DHL Stormers flanker Fourie was a key figure at the breakdown, as was Clermont counterpart Alexandre Fischer as turnovers regularly halted any attacking progress.
Belleau dispatched two penalties to see Clermont six points clear by the half hour mark, with the TOP 14 side’s robust defence frustrating DHL Stormers.
But the hosts would half the deficit moments before the break as fly-half Wolhuter, who was off target from range early in the game, nudged over the posts from halfway.
DHL Stormers drew level shortly after the restart as Wolhuter hit the target from the tee again, but Belleau struck an instant response for Clermont after more good work from Fischer.
However, Belleau was then shown yellow on 46 minutes as he was penalised for a deliberate knock-on, and it proved the turning point as DHL Stormers took full advantage of their extra body.
Two replacements notched their first two tries; flanker Roos powered over before scrum-half Jantjies finished well in the corner following terrific work from wing Suleiman Hartzenberg.
And a third score came before Clermont were back to their full complement, centre du Plessis producing a tremendous turn of pace to glide over after a smart offload from hooker Joseph Dweba.
Wing Delguy then hit back for Clermont as he raced clear from inside his own half with an hour played, but DHL Stormers secured the bonus point seconds later as Fourie dotted down amid a driving maul.
Replacement centre Sacha Mngomezulu was yellow-carded for a high tackle late on in a minor blemish on DHL Stormers’ evening, but the South African side will march into the knockout stage in their maiden Heineken Champions Cup campaign.