The Nizamiye Masjid  also known as the Nizamiye Mosque, is a Sunni mosque located in Midrand, part of Greater Johannesburg, in Gauteng, South Africa. It is widely regarded as the largest mosque in the Southern Hemisphere, occupying less than two-thirds of a hectare within a 10-hectare (25-acre) site.

Originally designed in Turkey, the architectural plans were later adapted by a South African architect to meet local building standards. Construction began in October 2009 and was completed in 2012. The mosque was officially opened by then-President Jacob Zuma on 4 October 2012.

The project was initiated by Ali Katırcıoğlu, a Turkish businessman who aimed to bring Ottoman-style architecture to places where it was not present. After failing to secure land in the United States, and on the advice of Fethullah Gulen, the project moved to South Africa.

Inspired by the 16th-century Selimiye Mosque in Edirne, Turkey, designed by Mimar Sinan, the Nizamiye Mosque is a scaled-down version at 80% of the original size. The central dome weighs 48 tons, stands 31 meters high, and spans 24 meters in width. Surrounding it are 21 smaller domes and 4 half-domes. The mosque also features four 55-meter minarets, each with staircases leading to three platforms.

The interior is richly decorated with Turkish calligraphy, handmade ceramics, and a custom carpet reflecting traditional Turkish art. There are 232 stained glass windows, and the mosque is illuminated in green and purple on special occasions.

The mosque can accommodate 6,000 worshippers and includes separate areas for men and women. The broader Nizamiye Complex also serves as a community center, offering various services and facilities including five wudhu (ablution) areas.