Sultan Suleiman Royal Mosque (Malay: Masjid Diraja Sultan Suleiman) is Selangor's royal mosque, which is located in Klang, Selangor, Malaysia. It was constructed by the British in the early 1932 and was officially opened in 1933 by the late Almarhum Sultan Sir Alaeddin Suleiman Shah.

This mosque combines various types of architectural styles (such as Moorish and Art Deco) and interior and exterior designs not replicated in other mosques around the country. Sultan Suleiman Mosque was the main state mosque of Selangor until the opening of Sultan Salahuddin Abdul Aziz Mosque in the new capital city of Shah Alam. Some of its interesting features include the Tangga Diraja (royal stairs) from Istana Alam Shah and a royal mausoleum. The late Sultan Salahuddin was buried in the mosque's grounds.

The design concept of the Sultan Suleiman Mosque is quite different from other mosques in the state, as well as in the rest of Malaysia's as it notably exhibits a combination of influences of Islamic architecture, Moorish, English, Neoclassical cathedral, and most importantly, Western Art Deco styles. It was designed by the British architect Leofric Kesteven (1882–1974), who was the Chairman of the Malayan Institute of Architects from 1931 to 1933, along with John Thomas Chester, the reinforced concrete specialist attached to United Engineers Ltd; and Rodolfo Nolli, the Singapore-based Italian sculptor who worked on the ornaments of the building