Eibar clinched the Segunda Division last term, having finished two points clear of Deportivo La Coruna, but saw their position in the top flight come under threat.
New financial rules stated the club must raise "share capital" of €1.7 million by August in order to take their place among Spain's biggest clubs.
While Eibar have the smallest ground in La Liga and a budget dwarfed by the likes of Real Madrid and Barcelona, they remain debt-free.
And, after selling shares to people from more than 48 different nations, the club have raised the money required to meet the financial stipulations.
Eibar's cause received widespread support from many in the game, including Real Madrid's Xabi Alonso.
The Spain international spent a season on loan at the Estadio Municipal de Ipurua from Real Sociedad and questioned the logic behind the rules in May.
"It is contradictory that a club who has an enviable financial health and with zero debts is obliged to do this, when there are others who have much deeper problems," he said.
"I hope we can put in a big push to keep them where they deserve to be."
