Dead-locked at 73-73 late in the fourth and the Bulls on the charge, James took over, scoring nine of Miami’s final 12 points to earn the Heat a split in the Windy City.
The best-of-seven series moves to South Beach for Games Three and Four Sunday and Tuesday.
“I put it all on the line tonight, I did whatever it took for our team to win,” James, who has been battling a cold, told reporters.
“I’m glad we’ve got a few days to get back down into that great weather we have in Miami.
“Hopefully I can get over it before we play Game Three. It’s whatever it takes at this point.”
James has made a habit of coming through in the clutch for the Heat this post-season in his chase for an elusive first NBA title.
Wednesday’s heroics mirrored those James delivered in the East semi-finals against Boston when he scored Miami’s last 10 points in a 97-87 win that eliminated the Celtics.
James finished with a game-high 29 points and 10 rebounds while Dwyane Wade contributed 24 points and nine boards.
Chris Bosh, the other member of the Miami’s big three, chipped in with 10 points and eight rebounds.
“That fourth quarter is going to be what will epitomize this entire series,” said Miami coach Erik Spoelstra. “It’s an absolute street fight.
“I anticipate a lot of quarters like that fourth quarter.
“I’ve seen it enough with Dwyane and now with LeBron that they respond and often play their best when their back is against the wall.”
Chicago got 21 points from Derrick Rose but the NBA’s most valuable player had little help, Luol Deng the only other member of the Bulls to hit double figures with 13 points.
The Bulls misfired on their first five shots but quickly found their groove led by nine quick points from Deng, who sank a half-court three at the buzzer to give Chicago a 26-19 first-quarter advantage.
A driving layup from James with seven seconds left on the clock allowed Miami to head into the intermission with a slim 48-46 lead, which they built up to 11 points in the third.
But the Bulls, backed by a vociferous capacity crowd, began to chip away at Miami’s lead and trimmed the deficit to 71-65 going into the final quarter.
Chicago opened the fourth with an 8-2 run to get back on level terms at 73-73 but would never retake the lead as James cuaght fire, ending the threat with five consecutive points to spark a final 12-2 run that iced the victory.
