After the 26-year-old midfielder agreed personal terms and successfully passed a medical Boro manager Gordon Strachan said: We're delighted to sign Nicky. He scores goals and all different kinds of goals.
He can play left-side of midfield or centre midfield and he's self-motivated. There's also a devil inside him when he plays and you sometimes need that.
Bailey scored 25 league goals in his two seasons with Charlton after joining them from Southend United.
He joins summer captures Andy Haliday and Kris Boyd who have bolstered Strachan's ranks ahead of their Championship campaign.
Source: Northern Echo
Source: Northern Echo