Liam McGowan, 22 and from the Co Leitrim village of Killough, had been on a life-support machine since the assault on August 20 last.
Killough parish priest Fr Thomas Keoghan said the death highlighted the “terrible violence in society and the lack of respect for human life”.
Mr McGowan lost his battle for life early yesterday morning surrounded by his loving family, including his heartbroken parents Martin and Maureen.
Two men have already been charged in relation to the assault.
A post mortem was being conducted on Mr McGowan yesterday.
A garda spokeswoman said that pending the result of the post mortem it would be a matter for the DPP to bring any further charges.
Mr McGowan was walking home after a night out when he was set upon near Hardwicke Street, in Dublin’s north-inner city.
He was struck from behind with an iron bar and robbed of a small amount of cash and his mobile phone.
He was found unconscious in a nearby alleyway at 2am on August 20. He was taken first to the Mater Hospital and later transferred to the intensive care unit at Beaumont Hospital.
Mr McGowan is survived by two older brothers, Padraic and Raymond, and girlfriend Laura Gavigan from Bundoran, Co Donegal.
He moved to a job with an insurance company in Dublin shortly after graduating with a commerce degree from NUI, Galway.
The village of Killough was in mourning yesterday and tributes poured in for the popular young man.
Fr Keoghan said: “We prayed for Liam. We even prayed for a miracle. But God’s way proved not to be our way.
“The sympathy of the entire community goes to Liam’s parents and his two brothers. It’s been a very difficult few weeks for them.
“His death brings home, sadly, the terrible violence in our society and the lack of respect for human life.”
Fr Geoghan added that while there was great grief there was no public display of outrage.
“But I’m sure that beneath the surface there is anger,” he said.
Mr McGowan was a pupil of De La Salle College in Ballyshannon, Co Donegal, before moving to Leitrim with his parents, where he was a noted footballer with Melvin Gaels.
Former principal Michael McGowan — no relation — said: “He was very friendly with a nephew of mine who was with him that night before this happened and that makes it more poignant to me. I had Liam as a pupil from first year to fifth year in De La Salle and he was a model pupil. It is so sad that life has been taken from him at 22. He was very intelligent but more importantly he was a very good lad.”