The 1958 Idaho gubernatorial election was held on November 4. Incumbent Republican Robert E. Smylie defeated Democratic nominee Alfred M. Derr with 50.96% of the vote.
Since changing to four-year term for governor beginning with the 1946 election, this was the first time the incumbent was permitted to run for re-election, due to a change in the state's constitution, approved by voters in November 1956. The last incumbent to be re-elected was C. Ben Ross, who won a third two-year term in 1934.
Primary elections were held on August 12, 1958.