Negros Occidental (Hiligaynon: Nakatungdang Negros; Tagalog: Kanlurang Negros), officially the Province of Negros Occidental (Hiligaynon: Kapuoran sang Nakatungdang Negros; Tagalog: Lalawigan ng Kanlurang Negros), is a province located in the western part of Negros Island in the Philippines. The provincial capital is Bacolod, a highly urbanized city that, while geographically situated within the province and classified as part of it by the Philippine Statistics Authority for statistical purposes, is administratively independent from the provincial government. Bacolod also serves as one of the two designated regional centers of the former Negros Island Region, the other being Dumaguete in Negros Oriental.

Negros Occidental occupies the northwestern portion of the island, sharing a land border with Negros Oriental to the southeast. The province is renowned for its significant contribution to the national sugar industry, earning it the moniker "Sugarbowl of the Philippines" due to its production of more than half of the country’s total sugar output.

Negros Occidental faces the island province of Guimaras and the province of Iloilo on Panay Island to the northwest, across the Panay Gulf and the Guimaras Strait. The primary language spoken throughout the province is Hiligaynon (also referred to as Ilonggo), while the predominant religious affiliation is Roman Catholicism, reflecting the historical influence of Spanish colonization.

The provincial capital and largest city by population is Bacolod, which serves as the administrative center of the province. However, it is classified as a highly urbanized city, rendering it administratively independent from the provincial government.

According to the , Negros Occidental has a population of 2,623,172 inhabitants, making it the most populous province in the Negros Island Region, the second most populous in the Visayas (following Cebu), and the 8th most populous province in the entire Philippines. It also holds the distinction of having the highest number of chartered cities of any Philippine province, with a total of thirteen.

The island of Negros was originally referred to by its native inhabitants as Buglas, a term in old Hiligaynon believed to mean "cut off", possibly referencing its geographic separation from the main islands. When Spanish explorers arrived in April 1565, they named the island "Negros" due to the dark-skinned Ati natives they encountered.

Among the earliest known native settlements were those in what are now the towns of Binalbagan and Ilog, which were officially established as towns in 1572 and 1584, respectively. Other notable pre-colonial and early colonial settlements included Hinigaran, Bago, Marayo (present-day Pontevedra), Mamalan (now Himamaylan), and Candaguit (now a sitio of San Enrique).

In 1743, Ilog was designated as the first capital of the province. The seat of government was later moved to Himamaylan before being permanently transferred to Bacolod in 1849. In 1890, the island of Negros was administratively divided into two provinces—Negros Occidental in the west and Negros Oriental in the east.