Ali Shukri Amin, 17, from the small town of Manassas an hour’s drive from Washington DC, will be subject to a lifetime of supervised release and monitoring of his Internet activities.
He is thought to be the first minor convicted in the United States of providing material aid to the extremist group, which has declared a caliphate in Iraq and Syria.
The prolific Twitter user, who sent more than 7,000 messages on the site in support of Islamic State, pleaded guilty in June.
Under the Twitter handle @Amreekiwitness, he provided IS supporters with instructions on using the virtual currency Bitcoin to conceal financial donations to the radical Islamist group and the best way to encrypt their online exchanges.
He also offered guidance to sympathizers seeking to travel to Syria to fight with IS, including another Virginia teen, Reza Niknejad, who traveled to Syria to join IS in January.
Niknejad, 18, was charged in June with conspiring to provide material support to terrorists, conspiring to provide material support to IS and conspiring to kill and injure people abroad.
US prosecutors welcomed the sentence.
Assistant attorney general John Carlin said “more and more” IS propaganda is seeping into American communities “reaching those who are most vulnerable.
“The Department of Justice will continue to use all tools to disrupt the threats that ISIL poses,” he said, using an alternative acronym for the group.
Those who use social media to support IS would be “prosecuted with no less vigilance” than those who take up arms for the group, said US attorney Dana Boente.
Amin’s lawyer, Joseph Flood, had described his client as a stellar student from a good family who was outraged by rights abuses under Syria’s President Bashar al-Assad.
When Amin pleaded guilty, Flood said he was the first minor convicted in the United States of providing material aid to IS.
In Florida, a 27-year-old Kenyan was sentenced to 15 years for conspiring to support Al-Qaeda, and its affiliates in Syria and Somalia, Al-Nusra Front and the Shebab, prosecutors said Friday.
Mohamed Hussain Said, who pleaded guilty in May, received wire transfers from a co-conspirator destined for Shebab and recruited experienced Shebab fighters to fight in Syria.
US prosecutors said he also tried to recruit others for attacks inside the United States.
On Thursday, another man was arrested in Arizona and charged with providing material support to IS for allegedly helping a New York college student travel to Syria to train for jihad.
The head of the FBI, James Comey, told lawmakers last month that upwards of 200 Americans have traveled or attempted to travel to Syria to join IS.