The 23 year-old midfielder from Cork made 142 appearances for the Pilgrims over the last three seasons and has been their Club captain since the 2012/13 campaign.
Hourihane came up through the youth ranks at Sunderland before making a move to Ipswich Town in 2010. The following season he moved to Plymouth where he built up an impressive reputation.
Last season Hourihane played 53 games scoring nine goals including two on the final day of the season against Portsmouth.
He has played for the Republic of Ireland team at both Under 19 and Under 21 level.
