Halford was farmed out to play-off hopefuls Charlton on a five-month loan spell last season and, after being unveiled at Bramall Lane, said he was looking forward to a run of games.
He said: "I enjoyed things at Charlton. I struggled to get games at Sunderland and then I went to London and played 14 consecutive games.
"It is nice to play and that is what I want to do - to show my potential.
"Promotion is the main aim. This is a massive club, great set-up and good players.
"I'm looking forward to a tough season but promotion is definitely on the cards. If we can hit the ground running and get a few early wins we will be up there."




