Corner Brook (2021 population: 19,316 CA 29,762) is a city located on the west coast of the island of Newfoundland in the province of Newfoundland and Labrador, Canada. Corner Brook is the fifth largest settlement in Newfoundland and Labrador, and the largest outside the Avalon Peninsula.

Located on the Bay of Islands at the mouth of the Humber River, the city is the second-largest population centre in the province behind St. John's, and smallest of three cities behind St. John's and Mount Pearl. As such, Corner Brook functions as a service centre for western and northern Newfoundland. It is located on the same latitude as Gaspé, Quebec, a city of similar size and landscape on the other side of the Gulf of St. Lawrence. Corner Brook is the most northern city in Atlantic Canada.

It is the administrative headquarters of the Qalipu Mi'kmaq First Nations band government. The Mi'kmaq name for the nearby Humber River is "Maqtukwek."

The area was surveyed by Captain James Cook in 1767. The Captain James Cook Historic Site stands on Crow Hill overlooking the city. By the middle of the 19th century, the population of Corner Brook was less than 100, and the inhabitants were engaged in fishing and lumber work.

The area was originally four distinct communities, each with unique commercial activities: Curling, with its fishery; Corner Brook West (also known as Humber West or Westside) with its retail businesses; Corner Brook East (also known as Humbermouth and the Heights) with its railway and industrial operations; and Townsite (known as Corner Brook) to house employees of the pulp and paper mill, laid out in 1923 by Thomas Adams using Garden City principles. In 1956, these four communities were amalgamated to form the present-day City of Corner Brook.

Between 1948 and 1958, about 70 people from Latvia and Germany settled in Corner Brook. They came as part of then Premier Joseph Smallwood's New Industries program. They built and worked at North Star Cement and the Atlantic Gypsum Plant. (For more history on the subject, see Latvians and Baltic Germans in Corner Brook.)

Corner Brook is home to the Corner Brook Pulp & Paper Mill (owned by Kruger Inc.), which is a major employer for the region. The city has the largest regional hospital in western Newfoundland. The Western Memorial Regional Hospital opened to patients and clients on June 2, 2024. It also has a wide array of shopping and retail businesses and federal and provincial government offices. It is home to Grenfell Campus, Memorial University, as well as campuses of Academy Canada and College of the North Atlantic.

Corner Brook celebrated its Come Home Year from July 19–28, 2019.