Athletic Bilbao B Women

In 2002, Athletic Bilbao introduced a women's section to their football activities, absorbing a local club Leioa EFT. At the same time they introduced a women's reserve team (which had been established by Leioa the previous year) with the aim of developing players for the senior side.

After a single season in the Basque provincial league, the B-team was promoted to the second tier – then known as the Primera Nacional – where they remained for two decades, winning their regional group in the competition four times (most recently in 2017) but being ineligible for promotion.

Athletic B, whose players are usually between 16 and 21 years of age, are also regular participants in the Copa Vasca, a regional tournament for lower-league teams, and have won the trophy six times.

Below the reserve level Athletic have a C-team, introduced in 2019 and quickly promoted to the Basque provincial league, and a girls' cadet (under-15) team, introduced in 2017 and competing at local youth level. In common with all other teams fielded by the club, only players who meet their recruitment policy of having a connection to the 'greater Basque Country' are eligible to join.

With the second tier re-organised in the early 2020s into two groups, then into just one, with a resultant uplift in the average standards (combined with general progress in the women's game in that period due to increasing investment and professionalisation), the teenagers of Athletic B began to find it difficult to remain competitive and it was no great surprise when they were finally relegated from the Primera Federación in 2023–24; this would have caused Athletic C to have been demoted, but they were also among the bottom places in their Segunda Federación group and would have dropped down in any event.