Mediate shot 1-under 71 to finish at 16-under 272 for his fifth victory on the PGA Tour and first since the 2000 Buick Open. It marked his second win at the Forest Oaks Country Club. He beat Steve Elkington in a playoff in 1993.
'Winning twice here is cool because this is a really hard golf course,' said Mediate. 'You've got to play good here, but today I kind of busted the odds. I think a lot of us did.'
Mediate also jumps from 21st to sixth on the 2002 money list with the $684,000 first-place prize.
'Today I had nothing,' he said. 'I just felt bad out there. I didn't feel like I could put the ball where I wanted to because I didn't know what the wind was going to do.
'It was just about survival. This was ugly and I just kept going forward and going forward. That's what's most satisfying to me.'
More from Rocco on his win
Calcavecchia (72) finished second despite matching the PGA Tour record for fewest putts in a 72-hole event. Kenny Knox also had 93 in the 1989 MCI Heritage Classic. The stat is a bit deceiving, however, as Calcavecchia hit just 50 percent of the greens in regulation over the course of the event.
'I must have putted 10 times in four days from an inch off the green,' said Calcavecchia, who went through a sneezing attack on the front nine due to the pollen in the air.
'It's luck obviously. I did putt great all week. I won't deny that. But to miss as many greens as I did is almost impossible on top of that. Hey, a record is a record, right?'
Calcavecchia started the day two shots back of Mediate, but pulled even through just four holes. That changed for good on No. 5 when Mediate birdied from out of the woods and Calcavecchia bogeyed for a two-shot swing.
The lead grew to four shots by the turn. Mediate went five up two holes later as Calcavecchia couldn't save par from out of the left woods.
Calcavecchia picked up a stroke on the 12th hole with a 35-foot birdie putt, but never got closer than three shots over the final five holes.
Full-field scores from the Greater Greensboro Chrysler Classic