Rhodes agreed to a one-year deal, a person familiar with the situation told The Associated Press. The person spoke on condition of anonymity because Indianapolis has not yet announced the deal.
The seven-year veteran had spent his entire career with Minnesota after the Vikings took him in the first round of the 2013 draft. He was selected to three Pro Bowls and was an All-Pro in 2017 when he had 56 tackles and two interceptions.
Colts general manager Chris Ballard has made a concerted effort to upgrade the defense this season. Last week, he sent a first-round draft pick to San Francisco for All-Pro defensive tackle DeForest Buckner. Ballard added another big body Wednesday by signing another former 49ers defensive tackle, Sheldon Day.
Rhodes joins the Colts after finishing last season with a career-high 63 tackles but with no interceptions for the first time since his rookie season. He could serve as a replacement for starting cornerback Pierre Desir, who signed with the New York Jets last weekend after being released by the Colts.
Rhodes has started 97 of 104 games and has 372 tackles and 10 interceptions in his career.