The Prince of Wales will take the salute when soldiers and veterans march through a city centre with their armoured vehicles.
Crowds are expected to pack the centre of Newcastle as members of The Queen's Own Yeomanry (QOY) parade with the Band of The Royal Regiment of Fusiliers.
The Prince is the Royal Honorary Colonel of the regiment - an armoured territorial army unit which is celebrating its 40th anniversary in 2011.
He will take the salute at Grey's Monument, in the heart of the city, as the unit exercises the Freedom of the City of Newcastle-upon-Tyne.
Charles will then meet the family and friends of those who have been on or are about to go on active service in Afghanistan.
The Honorary Freedom of Newcastle upon Tyne was originally given to the Northumberland Hussars in 1969, however the squadron became part of the Queen's Own Yeomanry in 1971.
The Prince will later join civic dignitaries at a Service of Thanksgiving at St Thomas the Martyr church.
The Lord Mayor of Newcastle, Councillor Geoff O'Brien, said: "We are delighted his Royal Highness The Prince of Wales will be sharing this special day with us and I am looking forward to welcoming him and the servicemen and women of the Queen's Own Yeomanry to Newcastle for this important occasion."
The Commanding Officer of The Queen's Own Yeomanry, Lieutenant Colonel Simon Graham, said: "It is a real privilege to be given the Freedom of Newcastle. The Queen's Own Yeomanry is celebrating 40 years as a Regiment in which they have deployed soldiers all over the world, wherever a conflict has taken place.
"We currently have 30 QOY serving alongside their regular counterparts in some of the most dangerous parts of Afghanistan."