In 2011–12, together with Peamount United, Cork Women's F.C., Raheny United, Shamrock Rovers and Wexford Youths, Castlebar Celtic became founder members of the Women's National League.[2][3] On 18 November 2012 Castlebar Celtic's manager, Jeremy Dee, died in a car crash while travelling to a league match against Shamrock Rovers. Dee was described as "the real driving force behind our women's team" by club secretary Michael O'Dwyer. He was also a leading advocate of women's association football in both County Mayo and Ireland.[4][5][6][7] While playing in the league, Celtic reached three cup finals. In 2013 they played in WNL Cup final, but lost 6–3 to Peamount United.[8] Later in the same year they reached the FAI Women's Cup final but lost 3–2 after extra-time to Raheny United.[9]
In 2014 they were WNL Cup finalists again but were beaten 3–0 by Wexford Youths.[10]
Withdrawal from leagues
Castlebar Celtic had planned to enter a team in the 2015 Mayo Women's Football League season but withdrew due to a lack of players.[11] During the 2015–16 Women's National League season they struggled. In October 2015 Castlebar Celtic failed to field a team for a WNL Shield game against Shelbourne Ladies.[12][13] During the course of the regular season Celtic had suffered two heavy defeats. On 10 October 2015 they lost 9–1 at home to Shelbourne Ladies.[14] Then on 2 January 2016 they lost 17–1 to Wexford Youths.[15] On 20 February 2016 they suffered a third heavy loss after losing 12–1 to Shelbourne Ladies in the WNL Cup[16] Before the season was finished they also withdrew from the Women's National League, again because they were unable to field a team.[6][7]