Jackson completed 37 of 43 passes in the 31-25 overtime victory at M&T Bank in Baltimore. He also ran for 62 yards to total more than 500 yards of offense. Colts quarterback Carson Wentz threw for 402 yards and two scores in the loss.
"I was just locked in," Jackson told reporters. "I was just calm. Everything was just moving slow, and I was just taking it a play at a time. That's what it was."
The game featured 1,036 yards of offensive and just two turnovers. Jackson became the first quarterback in league history to complete at least 85% of his throws and pass for 400 yards in the same game.
"It's one of the greatest performances I've ever seen," Ravens coach John Harbaugh said. "And it wasn't easy. It wasn't like we came out just up and down the field. We had to overcome and fight through some things.
"He was under pressure, and he created plays with his feet. He threw the ball away when he had to throw it away. Once we started. ... All the guys made plays and the offensive line, but it starts with Lamar. He deserves the credit."
The Colts took a 7-0 lead on a 76-yard touchdown pass from Wentz to running back Jonathan Taylor about two minutes into the game.
Ravens kicker Justin Tucker and Colts kicker Rodrigo Blankenship each made field goals at the end of the second quarter to make the score 10-3 at halftime.
Wentz increased the Colts lead with a 42-yard touchdown toss to Michael Pittman Jr. on the first drive of the third quarter. Taylor ran for a 4-yard score on the Colts' next drive for a 22-3 advantage.
The Ravens went on to score on each of their next four drives to complete the dramatic comeback. Jackson threw a 43-yard touchdown pass to wide receiver Marquise Brown with 56 seconds left in the third quarter.
Blankenship made a 43-yard kick at the start of the fourth to push the Colts lead to 16.
On the next drive, Jackson made a 5-yard touchdown pass to tight end Mark Andrews and again found Andrews for a two-point conversion, to cut the Colts lead to eight.
Ravens defensive lineman Calais Campbell blocked a 37-yard Colts field goal attempt on the next drive, and Jackson responded with an 11-play, 75-yard touchdown drive and two-point conversion.
In the final moments of the fourth, Blankenship missed a 41-yard, game-winning field goal to force overtime.
After the Ravens won the coin toss, Jackson engineered a 10-play, 68-yard touchdown drive on what would be the only possession in overtime.
Brown totaled nine catches for 125 yards and two touchdowns and Andrews had a game-high 11 catches for 147 yards and two scores. Taylor totaled 169 yards from scrimmage and two touchdowns on 18 touches for the Colts.
"I'm proud of the way our guys fought," Colts coach Frank Reich told reporters. "We are making progress. It's not good enough in this league to just make progress and lose tough games against tough opponents on the road.
"There is still a lot of good stuff going on. I know we have the right players and coaches in there. We just have to keep fighting to get better, learn from our mistakes and learn how to finish games."
The Ravens (4-1) next host the Los Angeles Chargers and the Colts (1-4) host the Houston Texans. Both games are scheduled for 1 p.m. EDT Sunday.