The theatre closed at the end of May 2005 for a major refurbishment, transformation, and it reopened on 7 October 2006 with a production of Verdi's Rigoletto. The Stalls area was completely re-seated and re-raked, the orchestra-pit enlarged, air-conditioning installed, backstage technical facilities dramatically improved, and Opera North now has an Opera Centre to the south of the theatre, accessible via a bridge and at street-level, which includes two new stage-sized rehearsal spaces and increased office space. The cost of the refurbishment has been estimated at £31.5 million.
A second phase of transformation included structural improvements and further refurbishment of the theatre and the restoration of the Assembly Rooms, a forgotten area on the first floor of the building that opened in 1879 and functioned as the Plaza Cinema between 1912 and 1978 and then as a rehearsal room for Opera North. With restoration now complete, the theatre has a second performance space, the Howard Assembly Room, which is used for recitals, concerts, chamber operas, experimental and educational work and other events for which the main theatre is unsuitable.
Since the "transformation" at the theatre, particularly after a state-of-the-art automated flying system was introduced, the theatre has been more able to host larger West End Musicals and plays.