Charlton Athletic were promoted to the Women's Super League for the first time after Sophie Whitehouse saved four penalties in a shoot-out to defeat Leicester City following a goalless draw in Saturday's play-off.
With the WSL expanding to 14 teams for next season, bottom club Leicester had one last chance to salvage their top-flight status against Charlton, who finished third in the WSL2.
But following 120 goalless minutes at The Valley, Emily van Egmond, Shannon O'Brien, Heather Payne and Noemie Mouchon all saw their spot-kicks repelled by the outstanding Whitehouse.
Charlton made the brighter start, going close when Emma Bissell shot wide of the far post, though Whitehouse made an excellent reflex save to deny O'Brien at the other end, on the stroke of half-time.
Leicester came out much the better team in the second half, though, with a series of attacking changes helping them take control.
They had Charlton penned back in the latter stages but were unable to avoid extra time, with their best opportunity for a winner in regulation being an Ashleigh Neville header that was well-held by Whitehouse.
Charlton went agonisingly close in extra time, as Katie Lockwood's venomous effort from distance thumped off the crossbar, and though Lucia Lobato was on hand to nod home on the rebound, she was marginally offside when the original shot was taken.
The Addicks were hanging on for penalties by the end of the additional period, and their goalkeeper was decisive in the shoot-out, making misses from Katie Bradley and Lucy Fitzgerald inconsequential.
Data Debrief: Leicester's miserable run goes on as Charlton take their place
Charlton, who missed out on automatic promotion on the final day of the season, will become the 21st different team to play in the WSL, while Leicester have been relegated from the top flight for the first time, having first played at that level in 2021-22.
The Foxes have now lost 12 consecutive games, while they are winless in their last 28 on the road in WSL competition (D8 L20), comfortably the worst run in WSL history.
Leicester might argue they were unfortunate, having posted 1.32 expected goals (xG) to Charlton's 0.29 over the 120 minutes, but their wastefulness from the spot cost them.