The Lions made the move Saturday, adding depth at the position bolstered by the addition of cornerback Justin Coleman in free agency earlier in the week.
Cooper closed last season with the Lions, playing in four games after appearing in two games early in the season with the Chicago Bears.
The 29-year-old Cooper has seven career interceptions in 74 games and 28 starts.
San Francisco drafted him in the seventh round in 2013 out of Rutgers and he had three interceptions as a rookie in Kansas City. After playing for the Chiefs for three seasons, he made 13 starts and had four interceptions for Arizona in 2016.