She served as a Teachta Dála (TD) for the Dún Laoghaire constituency from 1992 to 1997.

She was the daughter of Breandán Breathnach, a civil servant and collector of traditional music.

She also brought in the legacy posts, extra teaching positions for disadvantaged schools.

[5] After losing her Dáil seat in 1997, Bhreathnach was nominated by the outgoing Taoiseach, John Bruton, to the last days of the 20th Seanad.

She was a member of Dún Laoghaire–Rathdown County Council for the Blackrock local electoral area from 2004 to 2014.