The win advances the Packers (11-6) into a Divisional playoff game against the Philadelphia Eagles this Sunday at Philadelphia. By virtue of their No. 1 seeding, the Eagles (12-4) enjoyed a first-round playoff bye.
With what Packers head coach and general manager Mike Sherman said was an "all-out blitz," call by defensive coordinator Ed Donatell, Harris read the play and jumped in front of Seattle wide receiver Alex Bannister as the ball was being thrown.
Harris picked the pass off and then streaked down the sideline, outrunning both Bannister and Seahawks quarterback Matt Hasselbeck en route to helping the Packers keep their Super Bowl dreams alive.
"It came down to one play," said Sherman. "We make it, and fortunately, we win the game. It was two good teams battling it out. It could have gone either way."
The play came on the Seahawks' second possession of overtime.
Seattle opened the drive on its own 34-yard line and was able to get a key first down. But a run by Shaun Alexander for a one-yard loss, followed by an incomplete pass, set the Seahawks up at their own 45 as they faced a third-and-11 situation.
Sending a wave of blitzers, safety Marques Anderson scooted through the line and applied heavy pressure on Hasselbeck from the right side. Hasselbeck, trying to react quickly, turned to his left and zipped the ball towards Bannister, who was running a pattern tight along the sideline.
But Harris jumped the route perfectly and, knowing that he was about to put the game away for good, started celebrating by holding the ball in the air at about the 35-yard line.
"I was praying that it (would come my way)," said Harris, who finished with five tackles and a pass defensed. "Their quarterback made a lot of good reads because I jumped a lot of routes today.
"I was just thinking: ‘Don't drop the ball.' Two weeks in a row, I've dropped picks. I was looking to secure the catch and it was a foot race from there on."
It didn't look like Harris' heroics would even be needed since the Packers had set themselves up for what they were hoping would be a game-winning field goal by Ryan Longwell in regulation.
The Seahawks tied the game at 27-27 on a one-yard touchdown run by Alexander with under a minute remaining.
Green Bay then took over on its own 29-yard line with 45 seconds remaining and wound up driving the ball to the Seattle 29 with five seconds left, setting up Longwell's attempt from the right hash mark.
Longwell hit the ball well, but due in large part to a wind chill that had dipped into the single digits, his 47-yard attempt landed a few yards short of the cross bar as time expired.
"I said that we could try it from anywhere since it was the last play of the game," said Longwell, who had a nice game with field goals of 31 and 27 yards and moved into third place all-time in Packers history in playoff points scored with 55.
"When we got to the 30, I told (the coaching staff): ‘Five more yards.' I swung as hard as I could, got in on line. It was a great snap, a great hold, and I think we were a couple yards short."
The game was well played on both sides with the only turnover coming on Hasselbeck's interception.
Surprisingly, both teams struggled running the ball despite featuring two of the league's top backs in Alexander and Ahman Green.
Alexander did score three touchdowns, all one-yard runs, but he only rushed for 45 yards on 20 carries. As a team, the Seahawks were held to 49 yards on 21 attempts.
Green, meanwhile, scored a pair of touchdowns but rushed for just 66 yards on 23 carries. His second touchdown capped off a 12-play, 51-yard drive that melted over six minutes off the clock and gave the Packers a 27-20 lead with 2:48 left in the game.
Overall, the record-breaking Lambeau Field crowd of 71,457 saw scores that tied the game on four different occasions.
"I can't say enough about Seattle," said Packers quarterback Brett Favre, who threw for 319 yards and finished with a passer rating of 102.9. "It was well-played and well-coached. They played a helluva football game. It easily could have gone the other way."
The Packers tied the game at 20-20 on a one-yard touchdown run by Green with 10:01 remaining in the fourth quarter. The score was set up by a risky fourth-and-one call from the Seahawks' three-yard line.
Green, who converted on a two-yard, fourth-down run later in the quarter that set up his one-yard go-ahead touchdown plunge, took the handoff and scooted left on a sweep.
It looked like he was going to be dropped for no gain when Seattle linebacker Randell Godfrey wrapped Green up, but Green fought through the tackle and churned his way past the first-down marker before he was finally brought down by Godfrey near the goal line.
"That was a gutsy call," Favre said with a smile. "You're damned if you do, damned if you don't. Like I told Mike (Sherman) when I came off the field (after the touchdown): ‘Great call.'
Green Bay enjoyed a productive first half, managing 214 of its 397 total yards, but reached the end zone just once when Favre found tight end Bubba Franks from 23 yards out late in the second quarter.
Lined up tight on the right side of the line, Franks was supposed to run a corner route but read the defense and instead slanted in towards the middle, positioning himself in front of Seattle safety Damien Robinson, who had tripped on the play.
Franks found himself wide open and Favre delivered a perfect ball, putting the Packers ahead 13-6.
The pass marked the 14th straight postseason game in which Favre has thrown a touchdown, which established a new NFL record. Favre entered the game tied with Dan Marino.
It also moved Favre into third place all-time in NFL history with 31 career postseason touchdown passes. Joe Montana is first with 45, followed by Marino with 32.
Packers wide receiver Javon Walker continued to blossom into a big-play performer, catching five passes for a game-high 111 yards, which included a handful of crucial receptions.
Hasselbeck threw for 305 yards with receiver Koren Robinson catching seven passes for a team-best 88 yards.
"To be honest with you, I'm dying inside," said Seattle head coach Mike Holmgren. "It hurts. Initially, I was upset considering the circumstances.
"But when you look at the total picture, there's a lot more good than there is negative stuff to take away. The locker room is in tough shape right now. But the guys left it on the field. No one gave us a chance."