Morley Griswold was born in Elko on October 10, 1890. He earned undergraduate and law degrees from the University of Michigan and served in World War I. A leading attorney for corporations operating in Nevada, he formed a noted law firm that evolved into the Las Vegas firm of Jones Vargas. When Griswold entered politics, his business contacts became an issue and he faced conflict of interest allegations, particularly when he had clients tied to the collapse of George Wingfield's banks in 1934.

Griswold was elected to the first of two terms as Nevada lieutenant governor in 1926. He served with Governor Fred Balzar, who seemed to have faith in him, absenting himself from the state for long periods—such as three weeks in October 1931 for a hunting vacation with Jack Dempsey, followed by the Western Governors Conference. In 1932, it was actually Griswold who formally issued the bank holiday order for which Balzar was well-known, since the governor had been in Washington, D.C., to seek financial help for Wingfield's banks from the Reconstruction Finance Corporation.

Balzar's death in March 1934 made Griswold acting governor. Shortly thereafter, a formal attorney general's opinion issued on April 2 addressed the question of whether he could continue practicing law while serving as chief executive. Griswold was the Republican candidate for governor that year, but lost to Democrat Richard Kirman, so he served for only ten months.

During his period as acting governor, Griswold declined to call a special session of the Nevada legislature to deal with financing for upstream flood control on the Truckee and a federal/state dispute holding up construction of a new Ely post office. He forced out a state police inspector accused of shooting quail out of season, then refused to reinstate him after he was cleared of the charges.

Griswold was a delegate to the 1936, 1940, and 1948 Republican national conventions. He died in Reno on October 3, 1951.