The Guildhall Theatre is a grade II listed building situated opposite the Assembly Rooms. It is small and intimate venue that is predominantly used by amateur theatre groups and dance schools, in addition to hosting folk, comedy, children's, jazz and touring theatre events.

It has raked seating for 182 downstairs and a small balcony area seating a further 60. The balcony is not accessible to wheelchair or disabled customers.

There are large and small clubroom areas located adjacent to the venue, which can be used for small exhibitions, trade shows, CD/book fairs or that can be used in conjunction with the auditorium as additional dressing room space.

The Guildhall Theatre foyer space can be used for art exhibitions. Additional facilities include toilets, coffee shop and bar.