| Election Name: | 1966 United States Senate election in Michigan |
| Country: | Michigan |
| Flag Image: | Flag of Michigan.svg |
| Type: | presidential |
| Ongoing: | no |
| Previous Election: | 1960 United States Senate election in Michigan |
| Previous Year: | 1960 |
| Next Election: | 1972 United States Senate election in Michigan |
| Next Year: | 1972 |
| Election Date: | November 8, 1966 |
| Image1: | Robert P. Griffin 1969.png |
| Nominee1: | Robert P. Griffin |
| Party1: | Republican Party (United States) |
| Popular Vote1: | 1,363,530 |
| Percentage1: | 55.90% |
| Nominee2: | G. Mennen Williams |
| Party2: | Democratic Party (United States) |
| Popular Vote2: | 1,069,484 |
| Percentage2: | 43.85% |
| Map Size: | 300px |
| U.S. Senator | |
| Before Election: | Robert P. Griffin |
| Before Party: | Republican Party (United States) |
| After Election: | Robert P. Griffin |
| After Party: | Republican Party (United States) |
The 1966 United States Senate election in Michigan was held on November 7, 1966. Incumbent Republican U.S. Senator Robert P. Griffin, who had been appointed to the seat in May to fill the vacancy left by the death of Patrick V. McNamara, was re-elected to a full term in office. Griffin defeated Democratic former Governor G. Mennen Williams in the regularly scheduled election, as well as the concurrent special election to complete McNamara's unfinished term.