The battle for top-four positions and the minor premiership came down to the last game of the regular season between Queensland and the NSW Waratahs at Leichhardt Oval on Sunday.
The Reds, who had never beaten NSW, needed to win to move into the top four after the ACT Brumbies suffered a 36-20 defeat at Viking Park earlier in the day.
With the visitors holding their nerve to stun the Waratahs 26-19, the hoodoo-busting win helped them leap to fourth on the ladder.
Although Queensland scored three tries and were awarded a penalty try under the hammering rain in the first half, NSW stayed in the tense contest, closing the deficit to seven points early in the second half.
But a flurry of late errors for the Tahs cruelled their chances of a win, meaning the defending premiers dropped to third spot and will now travel to Perth to face the Force in the semi-final.
In the other semi, the Reds take on Fijian Drua, who claimed their first minor premiership since 2022, because NSW needed a bonus-point win to secure their fourth consecutive first-place finish.
"I've kept myself up the last two nights, and this is going to sound real cheesy, but ... I literally dreamt about this moment," Queensland flyhalf Lori Cramer told Stan Sport.
"It's huge for us ... and for all of the fans that have stuck by us this year, because we haven't had the performance that we've really wanted to show."
In Sunday's other match, ACT produced a spirited effort against the Force, but miss finals for a second consecutive year.
The Brumbies knew a win would be enough, but the Force scored six tries to three to book a home semi-final for the first time.
The Perth-based team had a dream start when hooker Hera-Barb Malcolm Heke and winger Vani Buleki scored within seven minutes.
But a red card to outside centre Cecilia Smith in the 12th minute opened the door for the Brumbies, and prop Linda Emelio wrestled over the line.
The visitors rebounded to find the tryline twice before the break while conceding one to lock Jess Grant in the 31st minute.
Leading 24-12 at halftime, the Force capitalised on a rolling maul to extend their advantage, and although the Brumbies' Paua-lee Going crossed in the 66th minute, substitute Taylor Waterson crashed over in the dying seconds to secure the bonus point.
SUPER RUGBY WOMEN'S SEMI-FINALS:
Fijian Drua (1) v Queensland Reds (4), July 18, Churchill Park, Lautoka
Western Force (2) v NSW Waratahs (3), July 18, TBC
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