The theatre, along with the neighbouring Garrick's Head public house, is a Grade II* listed building and is considered a prime example of Georgian architecture.
The oldest part of the building is the former Garrick's Head on St John's Close.
The three storey five bay building, with a basement, has a hipped roof with a part-balustraded parapet.
Above the door is a bust of David Garrick, which was made in 1831 by Lucius Gahagan.
The Beauford Square side of the building, originally designed by George Dance the Younger, is of five bays with pilasters carrying a frieze of comic and tragic muses.
The central door was the main entrance for the pit and galleries.
The east front, now the main entrance which opens onto Sawclose, was altered from a plain six-bay entrance by the addition of the round-arched foyer hiding four of the original bays.
The 900 seat auditorium has tiers of ornate plasterwork, with red and gilt decoration, and a trompe-l'œil ceiling and glittering chandelier.
It has three galleries in a horseshoe plan, supported by cast iron pillars.

In 2017 the Sawclose area between the current Theatre Royal main entrance and the former Bluecoat School was made into a pedestrian-friendly shared space area for pedestrians, cyclists and cars.
The theatre, along with the neighbouring Garrick's Head public house, is a Grade II* listed building and is considered a prime example of Georgian architecture. The oldest part of the building is the former Garrick's Head on St John's Close. The three storey five bay building, with a basement, has a hipped roof with a part-balustraded parapet. Above the door is a bust of David Garrick, which was made in 1831 by Lucius Gahagan. The Beauford Square side of the building, originally designed by George Dance the Younger, is of five bays with pilasters carrying a frieze of comic and tragic muses. The central door was the main entrance for the pit and galleries. The east front, now the main entrance which opens onto Sawclose, was altered from a plain six-bay entrance by the addition of the round-arched foyer hiding four of the original bays. The 900 seat auditorium has tiers of ornate plasterwork, with red and gilt decoration, and a trompe-l'œil ceiling and glittering chandelier. It has three galleries in a horseshoe plan, supported by cast iron pillars.
In 2017 the Sawclose area between the current Theatre Royal main entrance and the former Bluecoat School was made into a pedestrian-friendly shared space area for pedestrians, cyclists and cars.
Theatre Royal, Bath