Cardiff Met won 3-0 away to ten-player Cwmbran Celtic to become champions of Genero Adran South.
The Archers were a goal and a player up after just a dozen minutes, with the hosts having Summer Bowen-Quirk dismissed and Esme Kilburn-Thompson converting the penalty.
Molly Chapman doubled the advantage eight minutes after the interval, and Kilburn-Thompson later completed her brace.
The victory saw Cardiff Met move out of reach of second-placed Carmarthen Town, with two games to spare.
Next season they return to the top flight, where they have been the joint most regular champions, their six titles matched by Swansea City.
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