Ghana midfielder Baba Iddrisu and Real Mallorca sealed promotion back to the LaLiga on Tuesday after third-placed Almeria lost 3-2 at Cartagena.
The Balearic Island side make an immediate return to the top flight alongside Espanyol, who were also relegated last season.
Second-placed Mallorca are three points behind Espanyol, who were playing Ponferradina later on Tuesday, with three games to play and could go up as champions if the Catalans slip-up.
It is just the third time since 1990 that two relegated sides have secured promotion from the Segunda division to La Liga at the first time of asking.
After losing their first game of the campaign, Luis Garcia’s Mallorca side went 17 matches unbeaten.
They moved into the top two in November and have been there since, leading the table from January until April before being usurped by Espanyol.
The battle for the playoffs remains tense, with just six points separating Rayo Vallecano in seventh from Almeria.