The Muar District is a district in Johor, Malaysia. Muar is located at the mouth of the Muar River, on the coast of the Straits of Malacca. The Muar District covers 1,354 km2 (523 sq mi), with a population of 233,779 (2010).

Johor, is a state of Malaysia in the south of the Malay Peninsula. It shares borders with Pahang, Malacca and Negeri Sembilan to the north. Johor shares maritime borders with Singapore to the south and Indonesia to both the west and east. As of 2023, the state's population is 4.19 million, making it the second most populous state in Malaysia, after Selangor. Johor Bahru is the capital city and the economic centre of the state, Kota Iskandar is the state administrative centre and Muar serves as the royal capital.