Cowdenbeath retained their Championship status by beating Fife rivals Dunfermline 3-0 at East End Park in the play-off final on Sunday.
It was 1-1 from the first leg in midweek but the Blue Brazil made a dream start when Kane Hemmings scored after just 30 seconds to stun the big home support in the 8,288 crowd.
Thomas O'Brien doubled their lead midway through the second half and Greg Stewart sealed it with a third goal for Jimmy Nicholl's men with 13 minutes left.
Hamilton Accies will face Hibernian over two legs on Wednesday and next Sunday for a place in the Premiership next season.
Tony Andreu scored the only goal at New Douglas Park as Alex Neil’s men beat Falkirk 1-0 to progress 2-1 on aggregate.
Stirling Albion have been promoted to League 1 after beating East Fife 2-0 at Bayview to win 3-2 on aggregate.
Goals in the last 16 minutes from Jordan White and substitute Sandy Cunningham condemned Gary Naysmith's men to relegation.