Beacom struck out 17 and tripled to lead off the fourth ahead of Devine breaking a scoreless deadlock with the first home run of the event.
It was all Victoria needed to prevail 2-0 over New South Wales on Diamond 4 at Geelong Baseball Centre.
The first hit of the contest took until the bottom of the third as Beacom and NSW starter Lianna Davidson traded strikeouts.
Davidson finished with 14 strikeouts in a stunning pitchers’ duel in the battle for gold.
Both starters worked deep into the game, combining for 31 strikeouts.
Beacom allowed just one hit in 6 1/3 innings and offensively collected two of her own.
The 2018 Australian Women’s Baseball Championships continue with the Open Women’s final on Friday.