Dexter Blackstock agreed a three-year deal with the Millers just after the August 2016 transfer deadline.
The 30-year-old marksman left fellow Sky Bet Championship club Nottingham Forest after seven years at City Ground, before opting to join the Millers on a free transfer.
Blackstock, who began his career with Southampton, boasts a wealth of Championship experience following spells with the likes of Plymouth Argyle, Derby County and Queens Park Rangers.
In 2009 he made the move to Forest, following a successful loan spell, eventually racking up close to 200 appearances during his stay by the River Trent.
Blackstock made his Rotherham debut in the home game with Cardiff City in September 2016.