Andre Durie added a touchdown in the second half as the Argonauts beat the Stampeders before a loud home crowd of 53,208 at Rogers Centre on Sunday night.
Swayze Waters added two field goals for the Argos, who claimed their 16th Grey Cup and their first since 2004.
Calgary was limited to four Rene Paredes field goals and a safety touch.
Toronto built a 24-6 first half lead and never trailed in the game.
Owens opened the scoring as he took a pass from Ricky Ray on the right flats and ran in from the five-yard line 8:03 into the game.
The touchdown came after Jon Cornish fumbled an exchange with quarterback Kevin Glenn to give Toronto the ball on the Stampeders' 45. Calgary had failed to score after Quincey Butler picked off Ray's first pass of the game in the opening minute.
Larry Taylor returned the ensuing kickoff to the 40, then took a pass on the right side from Glenn for a 42-yard gain. After Cornish was held for short yardage twice, Paredes was good on a 30-yard field goal to make it 7-3 at 11:11.
The Toronto defence made 14-3 only 43 seconds into the second quarter on a 25-yard interception return. Glenn's pass was nowhere near Maurice Price and went to cornerback Horne, who wove his way into the end zone for his first TD of the year.
The Argonauts struck again on their next possession with Waters' 16-yard field goal at 5:56. The score was set up when Ray made a deft move to avoid a sack and found Jason Barnes alone up the middle for a 62-yard reception, the longest ever thrown by the veteran quarterback in his four Grey Cup appearances.
The Stampeders offence got going and Paredes made it 17-6 at 12:29. Nik Lewis did most of the work, catching a pass over the middle, slipping out of the grasp of Marcus Ball and heading for paydirt until Jordan Younger caught him at the 12 after a 61-yard gain.
The Argos struck right back to with Inman's touchdown with 20 seconds left in the half.
It was set up by Inman's catch at the one in tight coverage by Brandon Smith. The play was reviewed to see if Inman had scored, but the challenge was denied. After Chad Kackert was stopped on the run, Ray tossed to his lanky receiver for the score.
Paredes added a 27-yard boot at 8:52 of the third quarter on Calgary's first possession of the half with the help of Toronto's first two penalties of the game, which cost them 32 yards.
The Calgary kicker needed to make a tackle as Owens returned the ensuing kickoff to the 53. Seven plays later, including a 20-yard Kackert run, Waters' 20-yard kick made it 27-9 at 12:19.
Taylor looked to have returned the ensuing kickoff for a 105-yard TD, but it was called back on a holding call against Keon Raymond. But Rod Maver's perfectly placed punt put the ball on the Toronto two, leading to a safety as time expired in the quarter.
A 40-yard pass interference call against Ahmad Carroll put Paredes in place for a 19-yard kick to cut Toronto's advantage to 27-14 at 5:14 of the fourth.
But Calgary took 30 yards in penalties on a punt and Toronto re-established the 20-point lead as Durie took a pass and dove over the line for a seven-yard TD with 5:22 left to play.
Noel Prefontaine added a punt single with 1:28 remaining.
Calgary backup quarterback Bo Levi Mitchell hit Price with a late 12-yard touchdown pass and then the two combined on a two-point convert, but it was far too late to make a difference.
Toronto defensive tackle Adriano Belli, who intends to retire for a second time after the Grey Cup, was ejected at 12:49 of the third quarter for unnecessary roughness.