Rancho Johnson (or Johnson's Rancho) was a 22,197-acre (89.83 km2) Mexican land grant in present-day Yuba County, California, given in 1844 by Governor Manuel Micheltorena to Pablo Gutiérrez. The grant was located along the north side of Bear River, and encompassed present-day Wheatland. 
In 1844, Pablo Gutiérrez (died 1845), a Mexican who had worked for John Sutter since Sante Fe, was awarded the five square league land grant. As required, Gutiérrez built an adobe house (at the place afterwards called Johnson's Crossing). Gutiérrez was killed in 1845, and his property sold at auction by Sutter, as magistrate of the region, to William Johnson and his partner Sebastian Keyser (Kayser). Johnson took the east half of the grant, and Keyser the west. In 1846, they built an adobe house a short distance below Johnson's Crossing. Johnson’s Rancho, as it came to be called, was the last stop on the California Trail to Sutter's Fort. Seven members of the ill-fated Donner Party staggered into this ranch in 1847, seeking help for those left in the snowbound Sierra Nevada Mountains.
William Johnson (d.1863) was an English sailor out of Boston who for several years previous to this purchase, had traded between Hawaii and San Francisco. In 1847, Johnson married Mary Murphy (1831–1867), a survivor of the Donner Party, but they were soon divorced. In 1848 Mary married Charles Covillaud, owner of nearby Rancho Honcut, who named Marysville for her. In 1849 Johnson sold his share in the ranch to James Kyle, Jonathan B. Truesdale, James Emory, and William Cleveland, and went to Hawaii. Truesdale sold his interest to Cleveland, Kyle, and James Imbrie, who then sold to Eugene Gillespie and Henry E. Robinson.
Sebastian Keyser (d.1850), born in Austria, was a trapper who had accompanied Sutter in 1838 from Missouri, through New Mexico to California. Keyser went to Oregon but returned in 1841 to work for Sutter at his Rancho New Helvetia. Keyser was also the grantee of Rancho Llano Seco. In 1845 he settled on the Bear River as a half-owner of Rancho Johnson, and married Elizabeth Rhoads. Keyser sold his interest in the rancho to Eugene Gillespie and Henry E. Robinson in 1849. Keyser then operated a ferry on the Cosumnes River, where he drowned in 1850.
In 1849, Henry Robinson and Eugene Gillespie, who had title to the whole Rancho Johnson grant, laid out a town called Kearny, in honor of General Kearny. However the venture failed, and the town was never settled.
With the cession of California to the United States following the Mexican-American War, the 1848 Treaty of Guadalupe Hidalgo provided that the land grants would be honored. As required by the Land Act of 1851, a claim for Rancho Johnson was filed with the Public Land Commission in 1852, and the grant was patented to William Johnson in 1857.
- Ogden Hoffman, 1862, Reports of Land Cases Determined in the United States District Court for the Northern District of California, Numa Hubert, San Francisco
- Diseño del Rancho Johnson
- U.S. Geological Survey Geographic Names Information System: Johnson Rancho
- Hoover, Mildred B.; Rensch, Hero; Rensch, Ethel; Abeloe, William N. (1966). Historic Spots in California. Stanford University Press. ISBN 978-0-8047-4482-9.
- William Johnson The Donner Party:Rescuers and Others
- Meriam Marjory Murphy
- Mott v Smith, Reports of Cases Determined in the Supreme Court of the State of California, 1860, Volume 16, pp 533-559, Bancroft-Whitney Company
- Sebastian Keyser The Donner Party:Rescuers and Others
- Biographies Sutter's Fort State Historic Park
- History of Yuba County California, Thompson & West, 1879
- United States. District Court (California : Northern District) Land Case 397 ND
- Report of the Surveyor General 1844 - 1886