Despite finishing 26 points above them in the regular season, Pelicans were well beaten by Jukurit in the Playout, losing four matches in a row in a 4-1 series defeat.
That set up a meeting with Jokerit, who finished top of the pile in the second tier's regular season and backed up their dominance by winning the Playoffs.
A gulf in class between the top two divisions appeared evident when the Lahti side won 5-0 at home in game one, only for Jokerit to level with a hard-fought 4-3 win in second overtime in game two.
Back at the Isku Areena, Pelicans avoided a repeat of their Playout collapse by winning game three 2-0, before a crucial 4-3 overtime win in Helsinki put them on the brink of survival.
That gave Pelicans three chances to secure their Liiga place, though they only needed one in the end.
A 14th-minute goal from Lars Bryggman set them on their way, before Antti Tyrvainen put them in control in the first minute of the second period.
Elias Vilen made it three on a powerplay in the third period, before Konsta Hirvonen found the empty net late on despite his side playing shorthanded.
The 4-0 win meant all three home games for Pelicans in the series had seen them record a shutout, with Patrik Bartosak recording 26 saves in last night's victory.
It means another season outside the Finnish top league for Jokerit, who left in 2014 to join the Kontinental Hockey League, before returning to the Finnish system in 2023.
The Liiga Playoff Semi-Finals continue tonight, follow live updates on Flashscore.