Samuel Davidson King, Jr. was born in Washington, D.C. about 1843. He moved with his family to San Francisco and then to Nevada. His father, Samuel D. King, was appointed Recorder of Ormsby County in 1861 and remained in that office for several years. In 1873, Samuel D. King, Jr. was also appointed Recorder of Ormsby County.
He was elected District Judge of the Second Judicial District Court in 1878 and served through 1882. By 1890, King lived in Seattle, where he was a prominent lawyer for two decades. In 1916 he died in California. He was buried in Seattle with his wife, Fanny Clarke King