Originally built as a monument in 1965, the museum had a makeover and expansion in 1992 that combined constructivist and Melayu Islam Beraja (MIB) architectural elements.

Originally constructed as a monument, Royal Regalia Building (Muzium Alat Kebesaran Diraja) later underwent a transition into a museum.

Apart from the memorial museum, the building also housed an aquarium, then Brunei's historical and cultural centre, the office of the Department of Fisheries, and a lecture hall.

[2] Since 2 December 2017, the building has been renamed to the Royal Regalia Museum, in conjunction with the Golden Jubilee Celebration of Sultan Hassanal Bolkiah's ascension to the throne.

The memorial building's unique crescent form was maintained while the museum was being built, and original 1960s features including walls, stairs, verandahs, and banisters were integrated into the new structure.

The architecture of the museum expands smoothly from the original C-shaped structure, creating a dome-capped section and a semi-circular atrium.

The dome, which is the main feature, is decorated with golden flower mosaics called bunga putar, which mirror the clothing of the Sultan.

The 13.5 metres (44 ft) white spire of the dome, which symbolises protection and vigilance in Brunei's royal regalia, is shaped like an umbrella and draws inspiration from traditional Pemanjangan found in Istana Nurul Iman.

The walls are covered with large photos documenting significant national events and advancements over the Sultan's 75-year reign, along with recollections of his relationship with the populace.