Each one has its own design character, but they all contain a large gravel area where diners can play pétanque – the French game where players try to throw balls as close as possible to a target ball.
"The founder of Boulebar, Henrik Kruse, is a pétanque player himself," explained Johan Olsson, an architect at Bornstein Lyckefors.
"He fell in love with the sport during an inter-rail trip he made with some friends in Europe in the 1980s," he told Dezeen.
"When they came home, they opened a pétanque bar in Stockholm that they built themselves, without any permissions from the municipality. The idea grew, and from an underground pétanque bar, they became more and more professional."
The design for each venue starts with the idea of an indoor park.
Regular features include trees in large tubular pots and bench-style seats, painted in a colour the architects call Boulebar green. There is also a bespoke pendant light in all the venues, called Bend.
Elements are then added that fit this theme but also relate to the specific characteristics of the surrounding neighbourhood.
The new Copenhagen venue, for instance, features a range of playful details, including a bar that looks like an ice cream stand, a dining table shelter beneath a stripy awning and a set of red swings.
Another recently completed venue, in Stockholm's Rådhuset, is located beside the subway, so it has a more underground style with industrial finishes and graffiti-style murals by various street artists.
"The overall concept of objects in a room that you can move around – like objects in a park – has been part of the design all the way," said Olsson.
Areas are divided up into different spaces for dining, enjoying a coffee or having a cocktail, but the vibe is still very relaxed, to encourage diners to move around and socialise.
"Boulebar is operated by pétanque nerds and from the beginning the idea was not about creating success, it was more about the love of the sport," added Olsson.
"Today, it fits well within a larger trend of the hospitality industry where people tend to combine food and drink with activities such as bowling, table tennis and shuffle board."