HV 71 finished bottom of the pile in the regular season, but a run of four wins on the bounce has kept them in the top flight, while Modo must adjust to life in the Allsvenskan next season.
A 4-0 win in game five was perhaps the most decisive, as it was the only one of the six to be won by the away side on the night.
But the job was completed back at Husqvarna Garden, beginning with Oskar Stal-Lyrenas' opening goal inside the first five minutes.
One became two early in period two courtesy of Oscar Fisker Molgaard, before the fans in Jonkoping could all but taste victory at 04:41 in the second when Jonathan Ang made it 3-0 on a powerplay.
Those fans were in for a nervy third period, though, as Sampo Ranta got Modo on the board, before Samuel Vigneault made it 3-2 in the final minute.
But that was too little too late for the side from Ornskoldsvik, whose two-season stay in the SHL comes to an end.
In the Playoffs, Frolunda have taken a 2-1 lead over Timra but they needed a full 38 minutes and five seconds of overtime to do so in game three, to break the home fans' hearts.
Timra failed to take advantage of three powerplays in a scoreless first period, before eventually breaking through when the teams were even, three minutes into the second, through Erik Walterholm.
The Gothenburg side were struggling to keep their discipline, but that did not stop Max Friburg equalising five minutes later.
But Friburg was soon at fault for a delay of game, giving Emil Pettersson the chance to put Timra ahead again on a powerplay, before they went 3-1 up thanks to Magnus Paajarvi while shorthanded before the period was up.
Frolunda dug deep and got themselves back into the match late on courtesy of Arttu Ruotsalainen, who scored in the 57th minute, and then with just six seconds remaining to force overtime.
20 minutes was not enough to find a winner, and it looked as if 40 wouldn't be either, until 38:05 in overtime, when Isac Born scored his second of the series to win the match 4-3.
Timra will be looking to bounce back on Thursday, hosting game four at the SCA Arena.
After a 6-2 loss in the first match before hitting back with a 4-1 win two nights ago, Skelleftea have gone ahead in their series with Farjestad for the first time by taking game three 4-2 at home.
It was the visitors, however, who raced into an early lead through Michael Lindqvist, who broke the deadlock after 17 seconds.
But the game turned five minutes into the second period - down a man after Andreas Johnsson was penalised for charging, Skelleftea scored a shorthanded goal when Martins Dzierkals set up Par Lindholm.
Eight minutes later, the home side were in front when Jonathan Davidsson grabbed his first goal of the series.
Six minutes into the third period, Skelleftea roles were reversed when Lindholm picked up an assist for Dzierkals to score and give the hosts some breathing space.
Yet that lasted only five minutes when Linus Johansson struck for Farjestad to reduce the deficit, but their empty net gamble did not pay off - Rickard Hugg sealed the 4-2 win with an empty-netter.
The Skellefteå Kraft Arena will also host game four on Thursday.