The 27-year-old shot-stopper was technically a free agent after his previous contract with the club expired on 15 May.
However, after sitting down with new manager Jim Duffy this week, Gaston has elected to extend his stay at Cappielow.
Speaking to the Tele last night, he confirmed: “I’ve agreed to sign on again at Morton for next season.
“Jim Duffy phoned me and I then met with him on Monday to sort the contract out. It’s just a matter of going down to Cappielow to sign it now.
“[Chief executive] Gillian [Donaldson] is on holiday at the moment, so it will be a case of signing the paperwork when she gets back.”
After two seasons with the club, in which time he has made 60 starts and one substitute appearance, Gaston says it was an easy decision to stay for a variety of reasons.
He added: “A lot of teams just now don’t know what their keepers are doing, so you’d need to wait to find out if anyone else is interested in you.
“You could take a gamble and wait a few weeks to see what happens in the Championship but end up with nothing if it doesn’t work out for you.
“But that wasn’t the main thing for me anyway. I met with Jim and was impressed with what he had to say.
“He talked about how he wants to bring the team straight back up, and he convinced me that we’re going to be doing a lot better defensively.
“He said he’s going to be a doing a lot of work on the shape, so hopefully we’ll be doing a lot better between the goalkeeper and the defence than we did last season.
“He obviously knows what he’s talking about as a former defender himself, and I’m sure he’ll have the defence well drilled.
“That was quite an important thing for me.
“Another important thing was that I’ve already spent two seasons with the club — this will be my third – and I’ve really enjoyed my time here.
“If I hadn’t been enjoying it, I’d definitely have been looking elsewhere. I like going into my training and I like the people involved at the club, so it was also an easy decision in that respect.
“It’s also a bonus when the fans are on your side. If the supporters were giving you stick, you would maybe consider leaving to start afresh somewhere else.
“But I’ve always seemed to have a good relationship with the Morton fans – and hopefully they’ll still be on my side by next May, as that means I’ll have done a good enough job during the season!”