Karimunjawa Islands or Karimunjava Islands (Indonesian: Kepulauan Karimunjawa) is an archipelago of 27 islands in the Java Sea, Indonesia, approximately 80 kilometres northwest of Jepara. They have a total land area of 45.62 km. The main island is known as Karimun (2,700 ha), while the second-largest island is Kemujan (1,400 ha).

As of the 2020 Census, the population of the island group was 9,789 which lived on five of the islands. The official estimate as at mid 2022 was 9,926. The population is largely Javanese, with pockets of Bugis and Madurese inhabitants. Javanese culture is dominant in the islands which are the only islands off Java where Javanese is the lingua franca.

Twenty-two of the islands have been declared in 2001 as a marine reserve, the Karimunjawa National Park. Five more islands are either privately owned or are under the control of the Indonesian Navy.

The archipelago is served by Dewadaru Airport which provides scheduled airline services to Semarang and Surabaya.

The Karimunjawa islands comprise a district (kecamatan) which is made up of three villages (Karimun, Kemujan, and Parang) and forms a part of the Jepara Regency (kabupaten) of Central Java province. The island of Bawean lies east of this group, and is part of Gresik Regency, in East Java province.

Apart from use as a pirate base, the islands are believed to have been uninhabited until a penal settlement was established during the British occupation of Java in the early nineteenth century. Archeological finds of Chinese ceramics on the seabed near the islands which date from around the 13th century suggest that the islands were once part of a trade route to Java. The settlement was abandoned by the Dutch during the Java War of 1825–1830, but the former convicts remained as settlers. Coconut plantations set up during the convict period became a major source of income, as did fishing.

The islands were declared a national park in 1988.

The archipelago consists predominantly of pre-Tertiary continental islands primarily of quartzites and shales covered by basaltic lava. Geologically, the islands are part of Sundaland. The islands have extensive fringing and patchy coral reefs. The best time to visit the islands is during the dry season, generally from April to October.

The main source of income for the local population is fishing, followed by services and commerce. Travel to the islands from Java is sometimes limited during the rainy season around the January–March period during bad weather which can bring large waves to the area.

There are a number of snorkeling spots. There is pressure on local environmental resources because of the rapidly expanding tourist industry.