The 20-year-old represented the Red Rose at last summer's Junior World Championships in South Africa and was seen as a potential England senior international given his fine form on the domestic scene.
Heathcote was often picked above All Black World Cup winning hero Stephen Donald at The Rec prior to picking up a knee injury in the pre-season and he again showed his talents with a 21-point haul in the LV= Cup win over Newport Gwent Dragons a fortnight ago.
"I am delighted to be called up to the Scotland squad. I've always known I was eligible to play for Scotland and I'm grateful to be given this opportunity," said Heathcote, who joined up with his new team-mates last night.
"Tom has worked his way into the Bath first team squad from the academy and we've been monitoring his progress for the last couple of years," added Scotland head coach Andy Robinson, after he released five players, including outside-half Ruaridh Jackson, from the squad that lost to South Africa on Saturday.
Meanwhile, veteran Scotland prop Allan Jacobsen has announced his retirement from international rugby.
The 34-year-old loosehead has struggled with injury so far this term and wasn't involved in the 21-10 defeat to the Springboks.
He did feature as a replacement against the All Blacks a week earlier, though, when he won what has now been confirmed as the last of his 65 Scotland caps across a full decade of international service.
"To play international rugby you have to be absolutely committed," said Jacobsen, who will continue to play club rugby for Edinburgh having signed a three-year deal in 2010.
"You have to make sacrifices and do all the extra stuff in training and preparation to be right. I've always tried to do that throughout my career and playing for Scotland has meant the world to me.
"But the minute there is the possibility of it feeling like a chore, well, that's the slippery slope for me and I would never want to do anything that would either devalue the Scotland jersey or anything that I've achieved."