Founded on 30 November 1940, the team currently plays in the Segunda División, the second tier of Spanish football, having been relegated from La Liga at the end of the 2020–21 season.

[12] That season also included a historic moment when goalkeeper José Ignacio Garmendia scored a goal in a game against Pontevedra via a kickout from his own area.

In the 2012–13 edition of the Copa del Rey, Eibar ousted Basque neighbours Athletic Bilbao – who had appeared in two of the last four finals in the tournament – on the away goals rule to reach the round-of-16 following a 1–1 draw at the San Mamés Stadium.

[16] In 2013–14 Eibar earned, for the first time in its history, one of two direct promotion berths to La Liga,[17] which was certified on 25 May 2014 with a 1–0 home win against Deportivo Alavés.

[18] (they celebrated their feat with confetti originally produced by Barcelona, who wear the same colours and had anticipated winning the Spanish league title a week earlier, but that did not come to pass).

This included an inaugural ceremony on the pitch with a parade of 19th-century-clothed Basque soldiers with a Saltire and bagpipes playing "Scotland the Brave", with officials from both clubs shooting a 350 kg 19th-century cannon.

Borja Bastón finished top ten in scoring and was named La Liga Player of the Month of October 2015, making him the first Armero to receive the award.

In 2015, the club signed a collaboration agreement with CD Vitoria (Tercera División) to act as an Eibar feeder team for emerging players.

[26][1] Eibar had previously disbanded their own B team in 2012 to cut costs while the senior side languished in Segunda División B but decided to seek a new formal arrangement for a subsidiary club after retaining their place in La Liga.

[27] Within two years of the partnership, Vitoria gained promotion to the third tier for the first time in their history;[28] they were relegated in 2018–19[29] and their home matches back in the Tercera División were then moved to Eibar.

[41] Four players made the move that summer: goalkeeper Jon Ander, defender Amelibia, midfielder Sergio García and winger Thaylor.