In March 2015, Breen made her debut for the Republic of Ireland women's national football team in the 2015 Istria Cup, and also played in Ireland's match against Austria at the same tournament.[5] She had previously been called up to the squad for a winter training camp in La Manga.[5] In 2015, she played for Wexford Youths in the UEFA Women's Champions League; she scored four goals in a qualifying group stage match against Cardiff Met.[6][7] She was also part of the Wexford Youths team that won the 2015 FAI Women's Cup, the first time that Wexford Youths had won the tournament.[8] She was named in the Women's National League Team of the Season for the 2014–15 season.[9]
In January 2016, Breen was not selected in the Ireland squad for matches against the United States, as she was preparing to emigrate to Australia.[10] Breen returned to Australia later that year.[4]