The court heard that Ibad, who like many Indonesians goes by one name, received funding and guidance for the attack from Bahrum Naim, a radical Islamist linked to the January suicide attacks in Jakarta that left eight people dead.
Three others -- Sugiyanto, Saifudin and Yus Karman -- were also found guilty of terrorist offences in a Jakarta court and sentenced to four years and eight months over their role in the failed bomb plot.
"Ibad is Bahrun Naim's childhood friend," the lawyer Kamsi told AFP outside the East Jakarta courtroom.
"Naim lured Ibad to join him by saying it was easy to get a job in Syria, and told him to detonate a bomb in Solo."
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Naim sent cash via an Indonesian bank to fund the operation, the court was told. Ibad handled the cash and recruited the others to find a suitable target in Solo, a midsize city on the main island of Java.
A sustained crackdown in Indonesia, the world's most populous Muslim-majority country, weakened many of the most dangerous extremist networks responsible for a string of deadly homegrown attacks during the 2000s.
But the attack in downtown Jakarta earlier this year, the first claimed by IS in Southeast Asia, sparked fears of a resurgence in militancy.
Police alleged Naim masterminded the attack from Syria, where his exact whereabouts remain unknown. Four militants and four civilians died in the coordinated suicide bomb and gun attacks carried out in broad daylight in the Indonesian capital.