From 1941[2][3] until 1975,[2] the club was known as Atlético de Bilbao following a decree from the ruling regime of the period that foreign words should not be used – the Athletic name, adopted at the turn of the 20th century, reflected English connections to football in the area.

[15][16] That return ended in a 3–3 draw with Athletic progressing 6–5, although Honvéd played a portion of the match with ten men after the goalkeeper was injured; their international winger Zoltán Czibor took his place between the posts.

[15][16][17] Czibor, Sándor Kocsis and captain Ferenc Puskás did not go back and had to serve bans for their defection before they were able to play for their new clubs – Athletic's domestic rivals FC Barcelona and Real Madrid.

[18] The United players had helped to clear snow off their aeroplane at Bilbao Airport to enable them to fly home after the first leg;[19] exactly a year after their win over Athletic, the English club was decimated in the Munich air disaster which involved their plane failing on take-off in wintery conditions.

[20] It would be nine years before Athletic played in Europe again, although a Copa del Generalisimo win in 1958[21] and three league finishes in the top five (1958–59, 1959–60, 1961–62) achieved in the period would have been sufficient to qualify in later eras.

[28] That tie was successfully passed,[24][29] but after receiving a bye to the quarter-finals through the luck of the draw, Athletic's next opponents were Ferencváros who once more proved too strong, despite enduring a miserable journey from Budapest to the Basque Country for the second leg;[24] the Hungarians would again reach the final, this time losing to Leeds United.

[31][32] They overcame their first German opponents Eintracht Frankfurt through a spectacular volley from teenage defender José María Igartua[33] and advanced to the quarter-finals to face Rangers, where two late goals in the first leg at Ibrox proved decisive as the 4–1 loss,[31][34] including a strike by Alex Ferguson who had been in the Dunfermline side narrowly beaten four years earlier and had a goal disallowed in that tie,[23] was only countered 2–0 at home with some good chances to score a vital third being squandered.

[38] The change of competition to the UEFA Cup in 1971–72[39] brought little upturn in fortune, as Athletic qualified (their sixth successive European campaign, the longest sequence in club history) but lost to Eintracht Braunschweig[40][41] after beating Southampton.

[48] The tie was played in an unusually friendly atmosphere due to the similar regional identity of the two clubs,[49][50][51][52] whose supporters were excited by the prospect of a brighter future for their respective territories after the death of dictator General Franco and the weakening of his regime.

[44] Athletic's veteran goalkeeper José Ángel Iribar would face his 'twin', the Italian national custodian Dino Zoff (the two were of similar age, height and appearance).

[64] Results thereafter were not as impressive: the following season[39] began in familiar circumstances as Athletic defeated opponents from Switzerland (Servette) and Hungary (Újpest again, requiring extra time to progress)[65] before falling to Aston Villa,[65] and the 1978–79 UEFA Cup[39] run ended even sooner as Ajax overturned a two-goal deficit to win the first–round tie with Søren Lerby scoring the decisive goal with two minutes remaining.

[66][67] It was a fair outcome, as the second of Athletic's scores in Bilbao should not have been awarded: Juan Carlos Vidal's shot struck the outside of the supporting stanchion and rebounded onto the field of play in a similar manner to the legitimate goal earlier in the match, and was mistakenly given by the referee.

Facing Juventus once again (finalists in the previous three editions), Athletic managed to avoid defeat to the Bianconeri[88] but lost away matches to Rosenborg[91] and Galatasaray[92] to finish bottom of a very tight section.

Athletic, coached by Ernesto Valverde, made a comeback to continental competition in the 2004–05 UEFA Cup,[94][95] their only participation in that tournament's five-club group stage involving one match against each opponent.

[57][96][97] However, these positive results proved to be a false dawn as an underwhelming loss in the first knockout round to an Austria Wien side inspired by Libor Sionko followed.

In perhaps their most ignominious early exit, the only time they have fallen at a preliminary stage,[101] and (to date) the last of seven occasions where the team was eliminated from Europe after a playing just a single two-legged tie, a young understrength side lost to Romania's CFR Cluj in the opening round after both legs finished 1–0.

[102] The result came in the wake of the departure of two important players – Ezquerro to Barcelona[103] and Asier del Horno to Chelsea,[104] and set the tone for a disappointing domestic season in which the club narrowly avoided relegation after gaining 10 points in the last four matches.

[122] Athletic were then drawn against Manchester United and won 3–2 in the first leg at Old Trafford,[123] going on to knock the three-time European champions out of the tournament with a 2–1 victory at home (a long-awaited 'revenge' win from 1957).

A few hours after the match in Bilbao, an incident of disorder occurred near the stadium, during which Athletic supporter Iñigo Cabacas [eu] was shot in the head with a 'Flash-ball' fired by a member of the Ertzaintza police service and later died.

[131][132] Athletic lost the semi-final first leg in Portugal 2–1 after initially taking the lead through Jon Aurtenetxe,[133] but prevailed 3–1 at home with goals from Markel Susaeta, Ibai Gómez and the winner by Llorente in the 89th minute in front of a fervent home crowd to edge into the final in Bucharest, 4–3 on aggregate;[134][135] Bielsa's adventurous tactics[136] led to 28 goals being scored and 20 conceded across the six group games and eight knockout matches during the run.

[94] The qualifying rounds saw the team achieve both their biggest ever home win (6–0) against Finland's HJK,[151] and their highest aggregate margin of victory – the second leg finished 3–3 for a six-goal difference.

[152] The group stage was reached, but disappointing results, including two defeats to Lyon[29] and failure to beat debutants Hapoel Ironi Kiryat Shmona of Israel at home,[153] led to an early exit.

[155] After one season in a half-built stadium and with no European football, Athletic – now coached by Valverde for a second time – finished in 4th place in the 2013–14 La Liga, allowing rare access to the Champions League qualification process.

[88][95][156] However they could only finish third behind Shakhtar Donetsk and Porto[157] after losing to BATE Borisov[95][158] (who were defeated heavily by the other teams),[159][160] meaning they dropped into the Europa League, the only occasion in which the club has been involved in two European competitions in one season.

[162] In 2015, for the third time in seven years, Athletic lost the domestic cup final to Barcelona (who also won the league title);[95][163] UEFA's rules had recently changed, so they no longer qualified as runners-up.

[95] In the group stage they topped the section, only dropping points to AZ Alkmaar,[166][167] although it took two late goals from Aritz Aduriz to turn the away fixture with Augsburg on its head.

[191] The knockout draw provided a long trip to Moscow to face a fifth new opponent of that campaign, Spartak Moscow; a 3–1 first leg victory for Athletic in wintery Russia[192] proved too much for Spartak to overturn despite their 2–1 win in Bilbao, but the second leg of the tie was overshadowed by violent clashes between home supporters and travelling Russian hooligans before kick-off; a police officer collapsed and died from a heart attack in the efforts to control the scene.

[208] They also took part in the previous edition of the Supercopa and won the trophy,[209] but this was moved to the La Cartuja in Seville and played behind closed doors due to the COVID-19 pandemic in Spain.

The COVID situation also led to the two successive Copa del Rey finals for which Athletic qualified (with a Europa League place if won) being played within the space of two weeks in April 2021 in that same empty stadium; both of those matches ended in defeat,[210][211] but in the case of the 2020 final against local rivals Real Sociedad the European opportunity had already been forfeited due to both clubs voluntarily delaying the event in the hope that their supporters would be able to attend once rescheduled, which was ultimately unsuccessful.

Athletic performed strongly in the league phase, with victories from first-ever meetings with Slavia Prague, Ludogorets Razgrad, Elfsborg, Fenerbahçe and Viktoria Plzeň (and a win over AZ Alkmaar, an opponent nine years earlier), plus a draw away to Roma and only one defeat, to Beşiktaş in Turkey.