Spain's National Court, which deals with terrorism cases, found the man and three young women guilty of terrorist indoctrination in a ruling dated September 25 which was made public on Wednesday.
The four — two Moroccans, a Portuguese national and a Spaniard — were arrested in October 2015.
“This group used the social network Facebook to initiate its first contacts with its victims…. mainly young Muslim women,” the court said in its ruling.
The members then added the targets who seemed most promising to WhatsApp messenger service groups for further indoctrination.
The ring managed to convince at least one young Moroccan woman to go to Syria but she was arrested before she left Spain and sentenced to five years in jail for cooperation with a terrorist organisation.
The stiffest penalty went to the three women who were each sentenced to seven years behind bars.
The court found Sanae Boughroum, a 26-year-old Moroccan national, guilty of “exercising the ideological leadership” of the group as well as “spreading political and religious ideas that justified violence against people and good”.
She had planned to move to Syria as well to fight for IS, according to the court.
Two others, Laila Haira, a 23-year-old Moroccan national, and Saif Eddine Haik Aaniba, a 22-year-old Spanish national, were found guilty of running at least three WhatsApp groups with potential recruits.
The court also sentenced Fabio Miguel Medeiros Almeida, a 33-year-old Portuguese national who was in the process of being indoctrinated by the group, to four years in jail.
Almeida, who used the alias “Abderrahaman”, was arrested in Spain shortly after arriving from France to marry the leader of the ring.
Like other European nations, Spain has been grappling with a growing number of jihadist cells on its territory and radicalised Muslims leaving to join IS or other Islamist groups in Iraq and Syria.