James, who called the game "do-or-die" for his team, scored a game-high 32 points and Kyrie Irving added 30 as the Cavaliers breathed new life into a series that had looked headed for a quick finish after a lopsided opening two games in Oakland.
"We talked about effort for the last two days, just being aggressive, playing hard, the physicality, and we brought that," Cavaliers coach Tyronn Lue told reporters. "When we play that way, we're tough to beat."
Cleveland, well aware that no team in NBA history has ever come back from an 3-0 series deficit to win in seven games, got off to a fast start and led the entire way to keep alive their hopes of avenging last year's Finals defeat to the Warriors.
NBA Most Valuable Player Stephen Curry had a night to forget with 19 points on 6-for-13 shooting for the Warriors.
The Cavaliers were a much different team than the one that lost the first two games of the series by a combined 48 points and kept alive their hopes of delivering Cleveland its first professional sports championship in 52 years.
James and Irving set the tone early with a dominant first quarter, during which they helped Cleveland establish a 20-point lead at one stage.
The defending champion Warriors showed some signs of life in the second quarter as they chipped away at the Cavaliers lead, getting to within eight points by halftime despite Curry being held to two points.
However, Cleveland quickly squashed any hopes the Warriors had at making a comeback with a blistering start to the third quarter, where they built a 22-point lead after a jump shot by James with about six minutes left in the quarter.
The Cavaliers, embarrassed by a 33-point loss in Game Two, cruised the rest of the way and led by as many as 31 with a minute to play to change the narrative of a series that many had started to think would be over in four games.
"We weren't ready to play," Warriors coach Steve Kerr lamented. "Obviously, they just punched us right in the mouth right in the beginning.
"It's going to take more than an effort like that to win a Finals game against a great team, obviously."
