Shepherd, who led a race-high 124 laps, was making just his ninth career series start.
He became the fourth different winner in four visits by the series to the .375-mile Kawartha track. The 24-year-old from Brampton, Ont., won by a margin of 1.350 seconds over Kerry Micks.
Mark Dilley finished behind Kennington in fourth, followed by Don Thomson Jr.
Rounding out the top 10 were Scott Steckly, Jason Hathaway, Jeff Lapcevich, Ron Sheridan and Ron Beauchamp Jr.
The race was slowed due to caution eight times for 60 laps and the race lead exchanged hands 13 times among nine drivers.
The 33-year-old Kennington of St. Thomas, Ont., had twice finished as a runner-up in the championship standings (2007 and '09). With his title, he earned a starting spot in the postseason NASCAR Toyota All-Star Showdown.
Kennington, who came into the event with a 40-point lead over JR Fitzpatrick, gained third on the last lap after contact between Micks and Fitzpatrick for second led to a spin by Fitzpatrick in Turn 4. Fitzpatrick ended up in 15th.
The result was an 87-point margin in the final standings between Kennington and Fitzpatrick. Steckly, the 2008 champion, finished third in points, followed by Thomson, and Micks.
Mark Dilley finished behind Kennington in fourth, followed by Don Thomson Jr.
Rounding out the top 10 were Scott Steckly, Jason Hathaway, Jeff Lapcevich, Ron Sheridan and Ron Beauchamp Jr.
The race was slowed due to caution eight times for 60 laps and the race lead exchanged hands 13 times among nine drivers.
The 33-year-old Kennington of St. Thomas, Ont., had twice finished as a runner-up in the championship standings (2007 and '09). With his title, he earned a starting spot in the postseason NASCAR Toyota All-Star Showdown.
Kennington, who came into the event with a 40-point lead over JR Fitzpatrick, gained third on the last lap after contact between Micks and Fitzpatrick for second led to a spin by Fitzpatrick in Turn 4. Fitzpatrick ended up in 15th.
The result was an 87-point margin in the final standings between Kennington and Fitzpatrick. Steckly, the 2008 champion, finished third in points, followed by Thomson, and Micks.
The Kawartha 250 -- which will be telecast by TSN on Sunday, Oct. 10 at 1 p.m. ET -- was the final event of a 13-race schedule for the NASCAR Canadian Tire Series.