Kohles closed with a 1-under 70 to match Guthrie at 12-under 272 on Ohio State's Scarlet Course. Guthrie birdied three of the final five holes in regulation for a 66.
One of 12 college All-Americans invited to the event, Kohles turned pro after finishing his amateur career last week in the Porter Cup. The 22-year-old former University of Virginia player earned $144,000.
"It's absolutely a dream come true," said Kohles, the first player to win an event on the tour in his pro debut. "What more can you ask for in your first pro event than to win? It's still a bit of shock and I'm not sure it's all sunk in yet."
He moved into 13th place on the money list. The final top 25 will earn 2013 PGA Tour cards.
"Coming straight out of college I didn't have any money to my name, but I guess I have some now," he said.
Guthrie, from Illinois, also is a college All-America selection. He earned $86,400 and also has made $284,672 in three PGA Tour starts.
"There are a lot of good college players out there and a lot of good college programs," Guthrie said. "When we get out here we relish the moment. It's our chance to play well and show what we've got."
Casey Wittenberg, a