Sandakan District Mosque, Islamic religious center in Sandakan, Malaysia.

The Sandakan District Mosque, also called Masjid Besar Sim-Sim, stands in Sandakan, Sabah, and serves as the district's main mosque. It was built between 1985 and 1989 and officially opened in 1990. It is administered by the Sabah State Islamic Religious Affairs Department (JHEAINS).

Construction ran from 1985 to 1989, and the mosque was officially opened in 1990 as the main mosque of Sandakan district. It is administered by JHEAINS, the Sabah State Islamic Religious Affairs Department. In 2016 the Crown Prince of Perlis, Tuanku Syed Faizuddin Putra Jamalullail, visited the mosque.

The mosque serves as a central meeting place for Sandakan's Muslim community, especially during Ramadan and major Islamic celebrations when it draws worshippers from across the district. You can observe how people gather here to pray together and mark important religious occasions.

The location is easily accessible and features separate sections for different visitor groups, allowing for respectful visits. Guests should wear appropriate clothing and follow the etiquette of the place, particularly during the five daily prayer times.

The mosque is also known as Masjid Besar Sim-Sim, after the Sim-Sim area of Sandakan where it stands. It is administered by JHEAINS, the Sabah Islamic religious affairs department. In 2016 it received Tuanku Syed Faizuddin Putra Jamalullail, Crown Prince of Perlis.