The man was found with serious injuries on Hampton Wood Way on the St. Margaret’s Road in Finglas at around 12:30am.
The man in his 50s was rushed to the Mater Hospital where he was later pronounced dead.
A man in his 30s has been arrested and is being held under Section 4 of the Crimainl Justice Act.
The scene has been sealed off ahead of a forensic examination.
A post mortem is due to take place later today at Dublin City Mortuary.
Gardaí are appealing for witnesses or anyone with any information to contact them.
The Garda investigation is ongoing.
Main image: Gardaí. Image: Leah Farrell/© RollingNews.ie