Albion Rovers men defeated Queen's Park at Cliftonhill to march through on a 3-1 aggregate with Recreation Park seeing a goalless draw played out that resulted in Annan winning through 2-1 on aggregate and Alloa going down.
Paul Martin's Rovers side have not been out of Scotland's bottom tier since winning the old style Second Division back in 1989 and their relegation the following season has seen them spend 21 seasons battling for another step up.
That could all change following Saturday's win which was achieved through a brace of goals from one time Queen's Park player John Gemmell. The opening goal came midway through the second half after the Hampden men had gone close with an effort from Jamie Longworth and when play raced to the other end Robert Love released Gemmell who shot home.
Gemmell sealed the win in the final minute when he outsprinted the visiting defence and placed a shot behind Adam Strain to spark long-awaited celebratory scenes at the Coatbridge ground.
Martin said: "For a club like Albion Rovers that operates on a lesser budget than probably all of the clubs in the Third Division it is a great achievement to reach a play-off final.
"The effort from the players all season has left me humbled and their determination to win through was amazing."
Annan manager Harry Cairney, meanwhile, reckons his players showed they have grown into battled-hardened veterans of the SFL in the three years since they stepped up to replace Gretna, by keeping Alloa at bay in their second leg.
The blank scoreline saw the Galabank men progress thanks to their 2-1 home victory in midweek and Cairney praised his men, saying: "To reach the play-offs after such a short time in the league is a great achievement and credit has to go to the players."
Alloa had the better chances, but the signs emerged early on that it was not going to be their day early on. One of their two stand-in player/managers, Scott Walker, thought he tied the game after just 13 minutes, when his header beat visiting goalkeeper Craig Summersgill only for Steven Sloan to pop up on the line to boot clear.
And, on another day home, striker Jim Lister could have had a hat-trick.
A dejected Walker said: "The players have been fantastic in the two games Brown Ferguson and I have been in charge."