Singh won the event for the third time. He previously won it in 1993 and 1995.
In the final round, he shot 3-under-par 68 to finish 10-under 274.
"This was the biggest win for me in a long, long time," Singh said. "And it wasn't easy for me."
It was a confidence booster before next week's U.S. Open.
"There's a big tournament next week and I'll have to do exactly what I did today," he added.
Scott was 8-under 276 after shooting 1-under 70 in the final round.
"I hit a few too many bad shots today," Scott said.
For his first win of the season, Singh received $1,035,000.