The teen, who only recently celebrated his birthday, is believed to have died in a battle last week, with the news emerging in the Swedish media on Wednesday.
Full details about the boy's death have yet to be revealed and it remains unclear whether he was fighting in Syria or Iraq and whether he was a member of Islamic State (Isis) or another extremist jihadist groups
A family member confirmed to the Gothenburg Post newspaper that the boy had been killed.
"We knew nothing. I've just been told what happened and it's terrible," the relative said.
It's believed that the boy's brother is still alive and has made pledges online to fight with Isis (also known as the Islamic State) in Syria.
Citing unconfirmed reports, the newspaper stated that a number of other Swedish citizens were killed in the same clash.
Sweden's Security Service (Säpo) has said that there have already been over 100 confirmed cases of Swedes fighting with Islamic State and other jihadist groups. Between 20 and 30 Swedes have been killed in Syria and Iraq according to Säpo.
News of the boy's death fell on the same day that a high ranking member of Säpo spoke at a conference in Gothenburg, where he stated the city is over represented in terms of the numbers of young Swedish men who are electing to join radical Islamic groups in the Middle East.
Stefan Lindberg said that Säpo staff in the west of the country were working particularly hard to prevent potential recruits from heading overseas to fight.
"We can only try and persuade them. It is not illegal to choose to go into battle," Lindberg told the newspaper.
Earlier this month The Local reported that Säpo was concerned about the rapid increase in the number of Swedes going to fight with Isis
At the time, Sweden's head of Säpo Anders Thornberg said there had been an "explosive development" and claimed that up to 300 Swedes had travelled to countries including Afghanistan, Iraq, Yemen and Syria to fight for Isis.
In November three high school students were stopped at an airport in northern Sweden after booking a flight to Istanbul, following claims they planned to travel onwards to Syria to fight with Isis.