The Red Rose of Lancashire will fly from Bolton Town Hall on the 27th November to mark Lancashire Day.
Boundary signs will also feature the symbol — when they are renewed.
Friends of Real Lancashire (FORL) member Cllr John Walsh said he was delighted with Bolton Council’s announcement.
He said: “It is right that this council should show its historic links — after all our future is founded on our history.”
Cllr David Greenhalgh confirmed that the flag will be flown at the town hall on November 27 — and that signs around the borough will say ‘Bolton – part of the historic County Palatine of Lancaster’.
Bolton West MP Chris Green, an FORL patron, added: “Our town has a Lancashire identity and we ought to be proud of our roots.”
Horwich First town councillor Steven Chadwick, who describes himself as a ‘proud Lancastrian’, said the council’s decision was "great news”.
The civic town flag pole in Lever Park has already been flying the Lancashire flag for the last few months. Cllr Chadwick campaigned to include the words ‘Historic Lancashire Town’ on Horwich boundary signs.
He said: “Identity is important and any recognition of our towns’ shared red rose heritage is welcomed. No Act of Parliament has ever altered the boundaries of the County Palatine.
“Horwich and Bolton and all the other towns in the borough, while being in the administrative area of Greater Manchester are all also still within the ancient county of Lancashire.”
Mr Chris Dawson, Hon BSc, DLC Hons
Mr Philip Walsh
His Grace the Duke of Buccleuch
The Rt Revd Dr D.S. Walker, Bishop of Manchester
The Rt Hon The Lord Hoyle JP (Baron Hoyle Of Warrington)