Eric Wilson (27) was found guilty of the murder of Daniel Smith (24) last week by a jury in Malaga.
He was also convicted of the illegal possession of firearms. The written sentence is expected to be published at the Provincial Criminal Court today.
Wilson, from Ballyfermot in Dublin, was jailed for 23 years and ordered to pay €100,000 compensation to his victim's family.
Wilson is the prime suspect for a series of other killings. The Dubliner is believed to have been the hitman in at least three other murders and is on the shortlist of suspects for two more.
There are also suspicions that he was responsible for the murder in Spain of a Dublin criminal, who fled Ireland after a fatal double shooting in the capital.
Mr Smith, a roofer, died after being shot in the face and body with a 9mm pistol at the Lounge Bar in Riviera del Sol near the resort of Fuengirola on June 5, 2010.
He had rowed with Wilson after customer Georgina Hollywood accused the Irishman of touching her up.
Wilson raced home on his motorbike, grabbed the murder weapon from his rented home in Coin more than 30km away, and returned to kill his victim later that evening.