Jozef Puska has been found guilty of the murder of Ashling Murphy.
The defendant, of Lynally Grove, Mucklagh, Co. Offaly was mostly unmoved in the dock, and had his head down as the verdict was delivered before the Central Criminal Court.
After their deliberations, the jury of nine men and three women returned the guilty verdict.
Friends and family of Ashling Murphy applauded as the jury was dismissed by the judge Mr. Justice Tony Hunt.
Mr. Puska will be handed a mandatory life sentence, with a sentencing hearing to take place next week.
Women's Aid has welcomed the conviction saying this case is a "shocking example" of the dangers faced by women, and the case shone a spotlight on male violence in society.
Women's Aid says one man goes to jail today, but it will not bring Ashling back or compensate for her "heart-rending" loss.
However the organisation says effective criminal justice sanctions are "vital", and it truly hopes it offers some measure of justice and closure to Ashling's loved ones.
