The 65-year-old actress has claimed that she is "delighted" and "honoured" by the title, which she will receive for her services to drama and charity.
Johnston, who was born in Warrington, found mainstream fame in the 1980s when she starred alongside Ricky Tomlinson as Sheila Grant in Brookside. Her most famous role came as Barbara Royle in Caroline Aherne and Craig Cash's BBC One sitcom.
Her other TV credits include Inspector Morse, Goodbye Cruel World and Waking The Dead. She also starred in the big screen comedy Brassed Off.