Sheffield FC are the Women's Premier League champions after Lisa Giampalma's late goal sealed a 1-0 play-off final win against Portsmouth.
The results means that Sheffield will be promoted to Women's Super League Two, provided that they can meet the necessary licensing requirements.
Sheffield keeper Claire Wallhead made two fine saves to keep her side level.
And Giampalma won it in stoppage time, rounding goalkeeper Courtney Trodd before calmly slotting home.
Sheffield had the better of the chances in a goalless first half, striker Jodie Michalska dragging a left-footed shot wide before forcing Trodd into a superb save from long range.
After the break, Sheffield's Emma Johnson hit the side netting from inside the six-yard box, before captain Carla Ward saw her downward header cleared off the line.
Sheffield stopper Wallhead then produced a stunning save to keep out Lucy Quinn's looping effort, before Portsmouth captain Charley Wilson was then denied by another excellent save.
Substitute Abbie McIver blazed over for Sheffield after going through one-on-one, before Giampalma made no mistake in the closing stages to win a dramatic game.
Sheffield FC captain Carla Ward told BBC Sport:
"It is unbelievable. We have all stuck together and we've got there in the end.
"We always knew that, with one chance on goal, we had the ability to win it.
"I feel for Portsmouth. They were brilliant. It was just a case of trying to get in behind them, and we finally did."
Portsmouth first-team manager Perry Northeast told BBC Sport:
"It is difficult to speak. With the journey that this club has been through this season, for it to come down to added time at the end, that is cruel.
"Neither side played to just stay in the game. Credit to Sheffield, their goalkeeper made two fantastic saves. Both sides went out there to win the game.
"I can not be prouder. We have overcome so many barriers. The players have been absolutely magnificent."
Portsmouth FC Ladies: Trodd, Frampton, Bazan (Taylor), Clark, Currie, Bloomfield (O'Callaghan), Kempson, Sievwright, Quinn, Wilson (c), Hillier.
Substitutes not used: Goodall.
Sheffield FC Ladies: Wallhead, Cox, Murphy, Gilliat, Giampalma, Ward (c), Parkin, Goodman, Beanland (McIver), Michalska, Johnson.
Substitutes not used: Hogg, Johnson, Davies.
Referee: Lisa Rashid