The 21-year-old missed the tail end of last season with an ankle injury picked up in the Scottish Communities League Cup final defeat to Kilmarnock in March and had to watch from the sidelines as Neil Lennon's men recovered from that disappointment to clinch the SPL title.
However, Forrest is fighting fit again and after helping Celtic to a 2-1 home win over HJK Helsinki in the first leg of their Champions League third qualifier on Wednesday night, is keen to get going again against the Dons.
He said: "I'm back to full fitness now and I played most of the games in pre-season so I am feeling good.
"It was obviously a really good season for me and the team, although the last three months wasn't the best for me. But I am over that now and want to get on with the new season.
"We will have the fans behind us on Saturday and hopefully get them the three points.
"Aberdeen are a good team, they gave us a hard game every time we played them last season so it will be the same on Saturday."
With Old Firm rivals Rangers playing in the Irn-Bru Third Division this season, Celtic are overwhelming favourites to retain their SPL title.
Forrest admits he would relish drawing the Ibrox club in one of the cups, saying: "All the boys want to play in Old Firm games so if we did get them (in the cups) it would be good."
However, he dismissed the prospect of the championship turning into a procession for the Parkhead side.
"You can't think like that," he said. "The league isn't even started yet.
"We are just really focusing on ourselves and we want to make sure we win the league again and get into the Champions League again, that is the most important thing.
"I think there are four or five teams up there who will look to challenge us so I think it will be a competitive league."
