Wrexham clinched promotion to the Genaro Adran Premier with a narrow 1-0 win over Briton Ferry Llansawel.
Rebecca Pritchard scored the only goal of the play-off final between the winners of the north and south divisions in Newtown.
Pritchard netted in the 73rd minute but Wrexham had goalkeeper Delyth Morgan to thank for a handful of late saves.
Wrexham will return to the top flight after folding in 2016.
Having already sealed the Adran South title, Briton Ferry have a cup final date against Cardiff City next week and started the stronger at Latham Park.
Former Wales international Laura-May Walkey’s experience was telling, dominating in the middle of the park.
In contrast Wrexham, who comfortably won the north title with an impressive 100% record, looked nervy on the ball and uninspiring going forward.
Ferry also started the second half strongly with Lowri Baker twice going close.
However the breakthrough came on 73 minutes when Pritchard got her toe on the end of Rosie Hughes’ cross in the six yard area.
Hughes almost doubled Wrexham’s lead but her long-range effort hit the crossbar.
But Wrexham goalkeeper Morgan was eventually to prove the difference when Ferry’s Millie Jones found herself clean through.
Morgan palmed Jones’ effort wide before tipping Lucy Powell’s free kick onto the bar in the final minute as Wrexham held on for the win.
Wrexham’s squad are now due to turn semi-professional following promotion.
Steve Dale’s side attracted a record crowd of more than 9,500 at the Racecourse last month.
And the club’s Hollywood co-chairmen Ryan Reynolds and Rob McElhenney, who were at that game, pledged investment into the women’s programme when they took over in February 2021.
