Jeff Quinney took third place at 11-under par, followed by Jim Rutledge at minus-nine.
Grob held a one-shot lead over Kuehne at the start of Sunday's final round but quickly extended the margin. Grob posted a pair of early birdies and coupled with bogeys by Kuehne at 3 and 4, stretched the lead to four shots after five holes.
Kuehne bounced back to cut the lead to one after 12 holes but a bogey on 13 and a triple-bogey at 14 seemed to end the tournament. Grob made things interesting with a double-bogey at 15 but held on for the win.
'With Hank, no lead is ever going to be big enough,' said Grob. 'No lead is ever safe with him, and I knew he had holes coming home where he could make up some shots. He didn't play as well as he can, but all I kept thinking was I was playing with a guy that could break out at any time. We gave shots away to each other all day long, so I am just glad to get it over with me on top.'
'After falling behind early, I made some shots that got me right back into it,' said Kuehne, who shot a final-round 74. 'I just couldn't make the putts to close the gap, but that is the way it goes. I didn't hit it well enough to win a golf tournament. But my hats off to Mike- he got it done.'
Grob first broke into the winner's circle on the Canadian Tour at the 1997 Montclair P.E.I. Classic, and he followed that up with a win at the 1998 Canadian Masters.
Sunday's victory was also special for Grob because his 11-year-old daughter Dana was with him for the win.
'Dana was here with me at a Buy.com event in '99 and I ended up ninth, so she is turning out to be a little lucky for me,' said Grob. 'All I asked her for Father's Day was to let me win, and it looks like it worked.'
Alex Quiroz finished alone in fifth place at seven-under-par 281. Derek Gillespie came in sixth at minus-six, followed by David Hearn, who took seventh at five-under par.