The march is expected to be a “good-natured, fun family day.”
Dennis Clarke, Chair of YesCymru @ Y Barri, said: “The march taking place in Barry on 26 April 2025, will be a family-friendly affair where everyone is welcome.
“So mark your calendar now.”
The march will begin at 1 pm, with participants gathering at King Square.
The police and Vale of Glamorgan Council will manage traffic during the event.
The procession will set off from King Square, moving along Holton Road to the roundabout at the Millennium Bridge, passing the Memorial Hall, and continuing into Gladstone Road.
It will then proceed to the traffic lights at the junction with Ty Newydd Road before returning to King Square.
Marchers will be accompanied by several bands, and the pace will be “easy” to ensure everyone is comfortable.
Mr Clarke said: “We expect the event to be enjoyable and good-natured.
“Much music and banners with, perhaps, the odd whistle and flag.”
The event is more than just a march, with additional activities planned over the weekend.
Mr Clarke added: “More information will be given as the arrangements progress.
“It is not just a march.
“People will be attending from all over Wales and possibly further afield.
“We want to make their visit special - a visit to remember, a memory they can share with others when they return home.
“You are very welcome to come along and enjoy everything that is on offer.”