The Reds activated Hayes (back) from the 10-day injured list Friday, Charlie Goldsmith of Fox 19 Now Cincinnati reports.
Hayes looked sharp at the plate on his rehab assignment, going 7-for-12 with one home run in three games with Triple-A Louisville. He slashed an ugly .142/.195/.225 in 44 contests with the Reds before going down in late May with a bulging disc in his back. Hayes will get some starts at third base on days Sal Stewart plays another position, but it's uncertain how often Hayes will ultimately play.