Curwood was born in Owosso, Michigan, the youngest of four children. He left high school before graduation, but passed the entrance exam to the University of Michigan, where he enrolled in the English department and studied journalism. After two years, he quit college to become a reporter. In 1900, Curwood sold his first story while working for the Detroit News-Tribune. By 1909 he had saved enough money to travel to the Canadian northwest, a trip that provided the inspiration for his wilderness adventure stories. The success of his novels afforded him the opportunity to return to the Yukon and Alaska for several months each year that allowed him to write more than thirty such books.

By 1922, Curwood's writings had made him a very wealthy man and he fulfilled a childhood fantasy by building Curwood Castle in Owosso. Constructed in the style of an 18th century French chateau, the estate overlooked the Shiawassee River. In one of the home's two large turrets, Curwood set up his writing studio. He also owned a camp in a remote area in Baraga County, Michigan, near the Huron Mountains as well as a cabin in Roscommon, Michigan.

Curwood was an avid hunter in his youth; however, as he grew older, he became an advocate of environmentalism and was appointed to the Michigan Conservation Commission in 1926. The change in his attitude towards wild life can be best expressed by a quote from The Grizzly King: "The greatest thrill is not to kill but to let live."

In 1927, while on a fishing trip in Florida, Curwood was bitten on the thigh by what was believed to have been a spider and had an immediate allergic reaction. Health problems related to the bite escalated over the next few months and infection set in that led to his death from blood poisoning. Curwood was interred in the Oak Hill Cemetery in Owosso. At the time of his death, he was the highest paid (per word) author in the world.

Curwood Castle is now a museum. During the first full weekend in June of each year, the city of Owosso holds the Curwood Festival to celebrate the city's heritage. In addition, a mountain in L'Anse Township, Michigan was given the name Mount Curwood, and the L'Anse Township Park was renamed Curwood Park.

A great number of his works were turned into movies, several of which starred Nell Shipman as a brave and adventurous woman in the wilds of the north. Many films from Curwood's writings were made during his lifetime, as well as after his passing through to the 1950s. In 1988 French director Jean-Jacques Annaud used his 1916 novel, The Grizzly King to make the film The Bear. Annaud's success generated a renewed interest in Curwood's stories that resulted in five more films being produced in 1994 and 1995.