Miller, who played Aaron Livesy in the soap from 2008 to 2012, will take on the role of new regular Rob Waddington on the detective series.
The show is centred around main characters DC Rachel Bailey (Suranne Jones) and DC Janet Scott (Lesley Sharp), both of whom are members of the Major Incident Team of the fictional Manchester Metropolitan Police.
Spooks star Nicola Walker and Coronation Street's Tracie Bennett were announced to appear in series three of the crime drama last month.
Filming on the third series of Scott & Bailey began in November.
The new episodes will be set eight months on from series two's climax.