Chasing a target of 177, the visitors fell just short of the target despite a fabulous unbeaten 96 from 64 balls from captain Matthew De Villiers.
The Warriors slipped to 13-3 n the second over but De Villiers and Sinethemba Qeshile put on a rescue act with a stand of 75.
Qeshile was dismissed by seamer Ayabulela Gqamane (1-31) but Patrick Kruger then provided good support to his skipper.
Kruger though lost his wicket at a crucial stage, just as he was starting fond boundaries but had to walk back to the impressive spinner Imran Manack (3-25).
The game eventually came down to the final over with Ferisco Adams tasked to defend 18 runs while De Villiers was kept off strike and was denied a launch to the finish line.
Earlier, Boland posted a total of 176-3 in the 20 overs after skipper Clyde Reeves-Fortuin had won the toss and opted to bat first.
Gavin Kaplan top-scored for the hosts with a measured unbeaten 53 off 46 deliveries but the innings was given a late boost thanks to a cameo of 44 not out from 26 balls by Jhedli van Briesies.
Boland will host the final of the CSA T20 Challenge on Sunday while the Warriors will now to play the winner of the Eliminator clash between the Dolphins and Western Province.
Tristan Stubbs says he is excited to have an opportunity to play and work on one format of the game as he eyes hitting prime form for the Proteas at the T20 World Cup early next year.
The Warriors advanced to the CSA T20 Challenge final after rain washed out their clash against the Dolphins at St Georges' Park in Gqeberha on Friday.
The Warriors got a second bite at the cherry when they won a super over to defeat the Boland Rocks by ten runs in the CSA T20 Challenge Final in sunbaked Paarl on Sunday.
The Dolphins remain in the hunt for the CSA T20 Challenge title after a 15-run victory against Western Province at Kingsmead on Wednesday.
