Established May 23, 1857, and organized October 27, 1870, this county was named for William H. Nobles, who was a member of the Minnesota territorial legislature in 1854 and 1856. In the autumn of the latter year he began the construction of a wagon road for the U.S. government, crossing southwestern Minnesota and this county, to extend from Fort Ridgely to the South Pass in the Rocky Mountains. This work was continued in 1857 but was not completed.

Nobles was born in New York State in 1816; was a machinist by trade and came to St. Croix Falls, Wis., in 1841, to assist in building the first mill there but soon removed to Hudson, Wis.; in 1843 he began his residence in Minnesota, at Stillwater; and in 1848 came to St. Paul, where he commenced wagon making and blacksmithing, building for Henry H. Sibley the first wagon made here. In 1849 he went to California and lived there, in Shasta County, until May 1852, when he led a party of citizens to inspect a pass that he had discovered, crossing the Sierra Nevada, since bearing his name. Returning to Minnesota, he earnestly advocated the building of an immigrant road (and ultimately a railroad) from St. Paul, by way of the South Pass and Nobles Pass, to San Francisco. He served as lieutenant colonel in the Seventy-ninth New York Regiment during a part of the Civil War and afterward held several government positions. A few years of ill health ensued, and he died in St. Paul, December 28, 1876, having returned a few days previous from seeking in vain for recovery.

The U.S. steamship Nobles, named in honor of this county's Liberty Loan record in World War I, was launched August 23, 1919.