His Majesty's Theatre is an Edwardian Baroque theatre in Perth, Western Australia. Constructed from 1902 to 1904 during a period of great growth for the town, the theatre is located on the corner of Hay Street and King Street in Perth's central business district. At the time the theatre was opened, it was the largest theatre in Australia, and had seating for over 2,500 people. It is also thought to be the first reinforced concrete building constructed in Perth.