Mills carded a 2-under 70 to finish at 5-under-par 283 but the second-place check was enough to vault him into first place on the Canadian Tour Order of Merit.
The top two finishers on the money list after this week's Players Championship received exemptions into the second stage of PGA Tour Qualifying School. Mills became the first Canadian to win the money title since Masters champion Mike Weir in 1997.
'To be honest, coming into this week, I didn't look at it too closely,' said Mills, who won this year's MTS Classic. 'Finding that out is a big surprise. I figured I needed to win to even contend for first in earnings. It never even crossed my mind.
'To hear that Mike was the last Canadian to win, well, it's great just to be mentioned in the same sentence as him. He's a great player and a greater guy, so it's quite the compliment. And getting into the second stage is a huge relief and should take a lot of pressure off.'
Two-time winner on tour this season, Rob Johnson, tied for 18th Sunday but finished second on the Order of Merit to earn the second nod.
Butcher held a four-shot lead heading into the final round and was never challenged on Sunday. He tallied two bogeys through 10 holes but had a six- stroke cushion on the back nine at Wild Bluff Country Club.
Butcher recorded four birdies and a bogey on the second nine to win in only his fourth start in 2003.
'The toughest thing for me was coming out today like I didn't have a lead at all,' said Butcher. 'After the front side, I knew I pretty much controlled my own destiny. This is by far my biggest moment in golf.'
David McKenzie shot a 70 on Sunday and finished in third place at 3-under-par 285. Brad Sutterfield managed an even-par 72 but took fourth at minus-2.
Jim Lemon (72), Doug McGuigan (75), Mario Tiziani (74) and Chris Wall (74) shared fifth place at 1-under-par 287.