The 25-year-old was a regular in the team before he suffered a hip tear in December and was ruled out for the rest of the campaign.
But now after a successful operation and penning a two-year deal, McKay wants to repay boss Wullie Gibson with promotion back to the Championship.
He said: “I’m really happy, I’ve had a really good rehab thanks to the physio, the doctors and the club for getting the operation sorted. Wullie and the fitness coach getting up to speed. It was one of the main reasons why I wanted to sign back up.
“The fact they wanted to help me get through my rehab and they’ve put a lot faith in me. I want to repay them this season.
“I’ve had no problems with my hip since coming back, it’s actually felt really good and probably better than the season before when I was playing.
“It was hard watching last season and not being able to do anything on the pitch. Hopefully this season it can be different and get a full season in and take us up.
“I’ve played against both new signings Stuart Morrison and David McKay, they are both good lads and defenders. From what I’ve seen in training they’ll be good additions to the squad.
“Everybody at the club will say we want to get promoted and I’m no different.”