Sergeant Matt Tonroe was embedded with US forces when they were caught by an explosion on Thursday, the Ministry of Defence said.
The 33-year-old from Manchester was part of the 3rd Battalion the Parachute Regiment and had been deployed previously in Afghanistan and the Middle East.
Thursday’s explosion is reported to have taken place in the town of Manbij, 60 miles north east of Aleppo and close to the border with Turkey.
An American soldier was also killed and five other soldiers were injured by a blast while deployed against IS - also called Daesh.
Paying tribute, Defence Secretary Gavin Williamson said: “Sergeant Tonroe fought to protect British values, our freedoms and to keep us back at home safe. His sacrifice, unflinching commitment and bravery will never be forgotten.”
Sgt Tonroe’s Commanding Officer (CO) described him as a “deeply intelligent man and one of life’s characters”.
The unnamed CO said he had “served his country with pride and was a first class soldier, proven in combat, faced risk willingly and was ever ready for more.”
He added: “He thus died as he lived: daring and fearless in duty.”
His Officer Commanding, also unnamed, said: “He bristled with the contentment of a life lived to its full. His bravery and talent as a solider, was matched by his compassion as a human being.
“He was destined for great things in our unit; his leadership was both natural and apparently effortless. He is already missed.”
Sgt Tonroe is survived by his mother Michelle, his brother Alex and girlfriend Olivia, the Ministry of Defence said.