Johor (Malay pronunciation: [ˈd͡ʒoho(r)]), also spelled Johore , is a state of Malaysia in the south of the Malay Peninsula. It borders with Pahang, Malacca and Negeri Sembilan to the north. Johor has maritime borders with Singapore to the south and Indonesia to the east and west. As of 2023, the state's population is 4.09 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.

As one of the nation's most important economic powerhouses, Johor has the highest gross domestic product (GDP) in Malaysia outside of the Klang Valley, making it the country's second largest state economy, behind Selangor. It also has the second highest household income and total salaries among all states in Malaysia. Johor is a major manufacturing and logistics centre, with the largest transshipment hub in Malaysia, home to the Port of Tanjung Pelepas, the 15th busiest port in the world. Iskandar Malaysia, which covers much of southern Johor, is the country's largest special economic zone by investment value.

Johor has high diversity in ethnicity, culture, language, and is known for its traditional dance of Zapin and Kuda kepang. The head of state is the Sultan of Johor, while the head of government is the Chief Minister. The government system is closely modelled on the Westminster parliamentary system. The state is divided into administrative districts, with Johor Bahru District being the second largest district in Malaysia by population and economy. Islam is the state religion, but other religions can be freely practised. Johor has highly diverse tropical rainforests and an equatorial climate. Situated at the southern foothills of the Tenasserim Hills, inselbergs and massifs dominate the state's flat landscape, with Mount Ledang being the highest point.