The business fell in to difficulty last year but was bought back by several of its former directors in December, with the closure of its only London site.
Grillstock said in a Facebook post: “Grillstock is sad to announce the closure of the Bath Bar and Smokehouse after three very successful years of trading.
“The recent change of ownership has given the landlords the opportunity to buy back the lease from us... but the good news is that we will be moving to bigger premises soon!
“Thank you to all our guests for your support over the last few years. It has been an absolute pleasure to share our great BBQ meat with all of you.”
The company’s last day of trading at the restaurant was the 3 February.
A member of staff at the Bath site told The Bath Chronicle the group was trying to find staff jobs at its Bristol restaurants, but had had to make some redundancies following the closure.
Grillstock started out as a barbecue and music festival in Bristol, and opened its first permanent restaurant in the city in 2013.
It is left with two sites in Bristol and one in Leicester.
The site is believed to have been taken on pizza chain Franco Manca. The restaurant, which is expected to open before Easter, joins the group's other recently opened pizzeria in the south west, in Bristol, which has recorded strong sales at the start of this year.
This story has been updated to include information about Franco Manca.