He was struck by a bus that was heading south on Church Street at approximately 8.10pm on Saturday.
The 58-year-old female driver of the bus was taken to Wishaw General Hospital as a precaution.
Paying tribute on Facebook, the Harthill Community page said: “Our thoughts and prayers are with the family of Jay Gallacher following the tragic accident on Church Street yesterday evening.
“We are sure the thoughts of everyone in the village is with them at this time also.”
A GoFundMe page has also been set up in honour of Jay and to help fund his funeral and a memorial.
Road policing officers are now investigating the circumstances of the fatal crash.
Appealing for witnesses, Sergeant Ryan McAuley said: "A teenager has lost his life as a result of this collision and our thoughts at this time are with his family and friends.
"It is imperative that we establish the full circumstances surrounding the incident.
"A number of people were in the area at the time and we are asking those who have not already spoken to police to get in contact with us.
"You may also have dash-cam footage and we would ask you to check back and come forward with it."
Anyone with any information is asked to contact police by calling 101, quoting incident number 3610 of Saturday June 5 2021.
Additional reporting by PA