Ambon Island is part of the Maluku Islands of Indonesia. The island has an area of 743.37 km² (287.02 sq mi) and is mountainous, well watered, and fertile. Ambon Island consists of two territories: the city of Ambon to the south, and three districts (kecamatan) of the Central Maluku Regency to the north. The main city and seaport is Ambon (with a 2020 Census population of 347,288), which is also the capital of Maluku province, while those districts of Maluku Tengah Regency situated on Ambon Island had a 2020 Census population of 128,069. By mid 2023 those populations were estimated to have become 354,052 and 128,754 respectively, resulting in an all-island population of 482,806.

Ambon has an airport and is home to the Pattimura University and Open University (Universitas Terbuka), state universities, and a few private universities, which include Darussalam University (Universitas Darussalam, UNDAR) and Universitas Kristen Indonesia Maluku (UKIM).

The precious, highly expensive and sought-after veneer, named as Amboyna, has taken its name from Ambon Island, where much of the figured wood is believed to have been initially exported to Europe, North America and elsewhere.

Ambon Island lies off the southwest coast of the much larger Seram island. It is on the north side of the Banda Sea, part of a chain of volcanic islands that encircle the sea. It is 51 kilometres (32 miles) long and is of very irregular shape, being almost divided in two by a large inlet (Ambon Bay). The southeastern and smaller portion, (thereby forming a peninsula called Leitimur) is united to the larger northern portion (called Leihitu or Hitoe) by a narrow neck of land. The Ambon Bay thus formed cuts about 20 kilometres (12 mi) into the island with the airport on the northern shore and the city of Ambon on the northern, eastern and southern sides. The city of Ambon covers the entirety of Leitimur, with its centre on the northwest coast of Leitimur, but also includes the south-central part of Leihitu, and has a safe harbor on Amboina Bay.

The highest mountains, Wawani at 1,100 metres (3,600 feet) and Salahutu at 1,225 metres (4,019 feet), have hot springs and solfataras. They are volcanoes, and the mountains of the neighboring Lease Islands are extinct volcanoes. Granite and serpentine rocks predominate, but the shores of Amboina Bay are of chalk and contain stalactite caves.

Wild areas of Ambon Island are covered by tropical rainforest, part of the Seram rain forests ecoregion, together with neighboring Seram. Seram, Ambon, and most of Maluku are part of Wallacea, the group of Indonesian islands that are separated by deep water from both the Asian and Australian continents and have never been linked to the continents by land.

As a result of this isolation, Ambon has few indigenous mammals; birds are more abundant. The insect diversity of the island, however, is rich, particularly in butterflies. Seashells are obtained in great numbers and variety. Tortoise shell is also exported. The coast of Ambon is identified as a site of highest marine biodiversity importance in the Coral Triangle.

The population of the island (administered as Kota Ambon in the south, and Kecamatan Leihitu, Kecamatan Leihitu Barat, and Kecamatan Salahutu in the rural north) was just below 441,000 in the 2010 Census, but by 2020 had risen to over 475,000, and was over 482,800 in mid 2023. This included three tiny and sparsely populated islands (Lain, Hatala and Ela Islands) off the northwest coast,