The deficit to Lee Westwood with 18 holes to play was only one but Mickelson produced a bogey-free round with five birdies to usurp the Englishman at the top of the leaderboard and seal the title.
The left-hander became overcome with emotion and shared a long embrace with wife Amy just off the 18th green.
"I was just really glad she was there - I wasn't sure she was going to be - and it's something that I'll look back on and just cherish," he revealed.
"To have Amy and my kids here to share it with, I can't put into words. It just feels incredible, especially given what we've been through in the last year."
'Emotional' Mickelson accepts Green Jacket
It has been almost a year since Amy has been battling breast cancer and in that time Mickelson has alternated between playing golf and taking time off to be with her and his mother who was diagnosed with the same condition.
His form subsequently dipped and, coming into the Masters, he had failed to win a single tournament this year.
The American, who was dressed entirely in black with a pink ribbon stitched on to his cap to promote breast cancer awareness, added: "To be able to share this kind of joy means a lot to us.
"I don't normally shed tears over wins and when Amy and I hugged off 18 that was a very emotional moment for us and something that I'll look back on and just cherish.
"I'll cherish every moment of this week.
"To go through all that and come out the other side is something very special.
"My family has been through a lot this year and it means a lot to share some joy together. She's an incredible wife and an incredible mother. It's been amazing to have her here with me. It's something we'll share for the rest of our lives."
Mickelson shed tears when he hugged Amy after sealing his victory
Mickelson, who won the Masters in 2004 and 2006, effectively wrapped up the title with back-to-back birdies from the par-three 12th.
He narrowly missed an eagle from only three feet at the par-five 13th, after hitting a stunning shot with a six-iron from 207 yards through a four-foot gap between two pine trees, before holing out from a similar distance coming back.
That put him two strokes clear before he picked up another shot at the par-five 15th, where he reached the green in two and two-putted, to tighten his grip on a third Green Jacket.
"I had a good lie in the pine needles," he said of his remarkable shot on the 13th.
"I was going to have to go through that gap if I laid up or went for the green. I was going to have to hit a decent shot.
"The gap was a little bit wider - it wasn't huge, but it was big enough for a ball to fit through.
"I just felt like at that time, I needed to trust my swing and hit a shot, and it came off perfect."
"When I get here to Augusta, I get very relaxed and feel very comfortable," said Mickelson, whose fourth major title puts him one ahead of Ernie Els, Vijay Singh and Padraig Harrington and behind only Woods in the modern era.
"I'm in love with this place and it brings out the best in me."
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