Olivia Dillon (born 4 May 1973) is an Irish racing cyclist.
She competed in the 2012 UCI women's road race in Valkenburg aan de Geul and in the 2013 UCI women's road race in Florence.Dillon won her national tour, Rás na mBan, on three occasions: 2010, 2011 and 2013.
She is the only rider to win the event on more than one occasion. Dillon won the Elite Irish National Time Trial Championships on four occasions: 2008, '09, '10 and '12 and she took victory in the Elite Irish National Road Race Championships in 2010, one of five medals she won in the event.