Rex Beach was born in Atwood, Michigan, but moved to Tampa, Florida, with his family where his father was growing fruit trees. Beach was educated at Rollins College, Florida (1891–1896), the Chicago College of Law (1896–97), and Kent College of Law, Chicago (1899–1900). In 1900 he was drawn to Alaska at the time of the Klondike Gold Rush. After five years of unsuccessful prospecting, he turned to writing.

      His second novel The Spoilers (1906) was based on a true story of corrupt government officials stealing gold mines from prospectors, which he witnessed while he was prospecting in Nome, Alaska. The Spoilers became one of the best selling novels of 1906.

      His adventure novels, influenced by Jack London, were immensely popular throughout the early 1900s. Beach was lionized as the "Victor Hugo of the North," but others found his novels formulaic and predictable. Critics described them as cut from the "he-man school" of literature: stories of "strong hairy men doing strong hairy deeds." Alaska historian Stephen Haycox has said that many of Beach's works are "mercifully forgotten today."

      One novel, The Silver Horde (1909), is set in Kalvik, a fictionalized community in Bristol Bay, Alaska, and tells the story of a down on his luck gold miner who discovers a greater wealth in Alaska's run of salmon (silver horde) and decides to open a cannery. To accomplish this he must overcome the relentless opposition of the "salmon trust," a fictionalized Alaska Packers' Association, which undercuts his financing, sabotages his equipment, incites a longshoremen's riot and bribes his fishermen to quit. The story line includes a love interest as the protagonist is forced to choose between his fiance, a spoiled banker's daughter, and an earnest roadhouse operator, a woman of "questionable virtue." Real life cannery superintendent Crescent Porter Hale has been credited with being the inspiration for The Silver Horde, but it is unlikely Beach and Hale ever met.

      After success in literature, many of his works were adapted into successful films; The Spoilers became a stage play, then was remade into movies five times from 1914 to 1955, with Gary Cooper and John Wayne each playing "Roy Glennister" in 1930 and 1942, respectively.

      The Silver Horde was twice made into a movie, as a silent film in 1920 starring Myrtle Stedman, Curtis Cooksey and Betty Blythe and directed by Frank Lloyd; and a talkie version The Silver Horde (1930) that starred Jean Arthur, Joel McCrea, and Evelyn Brent and was directed by George Archainbaud.

      Beach occasionally produced his films and also wrote a number of plays to varying success. In 1926 Beach was paid $25,000 to write a brochure entitled The Miracle of Coral Gables to promote the real estate development of Coral Gables, a planned city. In 1949, two years after the death of his wife Edith, Beach committed suicide in Sebring, Florida at the age of 72. In 2005, when the home Beach lived in was remodeled, a bullet was found in the wall, believed to be the bullet that ended his life.

      Beach served as the first president of the Rollins College Alumni Association. He and his wife are buried in front of the Alumni house.

      Beach, and his most famous novel, were commemorated in 2009 by the naming of a public pedestrian/bicycle trail in Dobbs Ferry, NY, a former place of residence. The trail is called "Spoilers Run".