Emer Costello (née Malone; born 3 September 1962) is an Irish Labour Party politician. She was a S&D Member of the European Parliament (MEP) for Dublin from February 2012 to May 2014. She was a member of Dublin City Council from 2003 to 2012, and was Lord Mayor of Dublin from 2009 to 2010.
A native of County Louth she has a B.A. and a H.Dip. in Education from University College Dublin.
She was first co-opted onto Dublin City Council as a member for the North Inner City area in 2003 to replace her husband, Joe Costello, who resigned following the end of the dual mandate. She was elected in 2004 and re-elected in June 2009. She was elected Lord Mayor of Dublin by a unanimous vote of the city council at its annual meeting on 15 June 2009.
Costello has observed international elections in Cambodia, South Africa and Bosnia.
Her sister is Senator Mary Moran.
Costello replaced Proinsias De Rossa in the European Parliament when he resigned as MEP in February 2012. She lost her seat at the 2014 European Parliament election.