Gardai confirmed the man was was arrested in the city centre this morning by officers investigating the assassination.
He is currently detained under the provisions of Section 30 Offences Against the State Act 1939 as amended at Tallaght Garda Station.
The 42-year-old was shot dead in Tallaght, south Dublin on January 18 of this year.
He was discovered by Gardai lying dead on the side of the Fox Hill Road, near Bohernabreena, with gunshot wounds to his neck and body.
Cops on patrol noticed a suspicious car at about 10.30pm and when they approached a chase ensued.
The other vehicle managed to evade gardaí and when the cops returned to the scene they found lying Devoy shot to death on the road.
He was still wearing the bullet proof vest that he wore to thwart another attempt on his life. Devoy had previously survived two attempts on his life in recent years.
Devoy was a veteran criminal who was extremely well-known to gardai and had earned the reputation of a very violent individual.
He is also the chief suspect in the murder of 30-year-old Mark Byrne in May 2005.
Byrne, who had just been released from Mountjoy prison, was walking out of a shop after buying phone credit when a gunman shot him dead. The murder was later recreated on RTE drama Love/Hate.
Devoy was arrested over the murder and gardai were hopeful there was enough evidence to charge him – but the DPP disagreed.
He had more than 70 criminal convictions and has served prison sentences over the past 25 years for making threats to kill, possession of firearms as well as burglary, driving offences and other public order matters.