After informing the Taoiseach of his intentions yesterday afternoon, the Cork North Central TD sent a letter to local members confirming that he would not contest a selection convention next month, and will step down at the next election.
Mr Murphy served as Lord Mayor in 2009 and was elected to the Dáil in 2011. He served as Minister of State for Europe from 2014 under Enda Kenny, but was dropped by Leo Varadkar when he became Taoiseach.
“I would like to thank you, all members of Fine Gael, for your continued support over the last 20 years that I have been involved in local and national politics,” reads the letter he sent to members.
He described his term as Lord Mayor as an “immense honour” and said it was a “privilege” to represent Ireland in Europe as a Junior Minister.
Deputy Murphy said: "This was a most interesting and challenging time, particularly with Brexit. I am very grateful for your immense support throughout this period.
He also reiterated his support for his party.
"I would like to underline my unequivocal support for the Taoiseach, this FineGael-led government and the Fine Gael party.
"It has unquestionably been the case that since our election into government in 2011, Fine Gael has delivered a period of excellent governance, through very difficult times.
"This leadership has now transformed our country and brought confidence back to our people. It has been a deep honour for me to represent the people of Cork and indeed our country during this time," he said.
Mr Murphy is expected to focus on organising the European election campaign for the European People's Party, Fine Gael's EU affiliate. He is a Vice President of the party and was appointed director of elections last year.
The attention of local members will now turn to the party's Cork North Central selection convention on Monday, June 18.
Senator Colm Burke and Mr Murphy's 2016 running mate, barrister Julie O'Leary, are both expected to contest the convention. The party has always run at least two candidates in the constituency.