The 30-year-old joined The Millers this summer and has made eight appearances in all competitions so far this season.
Born in Chelmsford, Halford started his career at Colchester United signing a professional contract in August 2002.
The defender made 163 appearances for the Essex side, where his performances earned big money moves to Reading and Sunderland as well as four caps for England at U20s level.
Halford made his Sunderland debut in a 2-2 draw against Blues at St. Andrew’s, but after only six months in Tyneside he joined Charlton Athletic on loan for the remainder of the season.
A season-long loan to Sheffield United followed and he once again made his full Blades debut at St. Andrew’s with Kevin Phillips securing all three points with a late winning goal in 2008.
Halford joined newly promoted Premier League side Wolverhampton Wanderers a year later for an undisclosed fee, before joining Portsmouth on loan.
In 2011, Halford’s loan became permanent and the defender finished the season as the club’s second top scorer in all competitions with seven.
He joined Nottingham Forest in 2012, scoring eight goals in 82 appearances until joining Brighton and Hove Albion on loan in November last season.