The event, at the Bus Depot on Broad Street, is on April 26 and will feature free rides for visitors on various heritage buses from 65 to 25 years old.
Mike Taylor, chairman of the heritage group, said: “We will be operating a frequent timetable with free heritage bus departures at least every 20 minutes and if its dry we will also run in additional open top buses.
“We are all volunteers and we aim to provide an interesting day for visitors, and we only ask for donations.
“All rides are free and entry to The Bus Depot is also free.”
The group has decided to run a full timetable between 10.30am and 4pm, even though the cost of diesel in their buses has increased by more than 35 per cent since the Iran War.
Mr Taylor said: ” We will be running several former Cardiff buses from the 1960s to the 2000s, long distance buses are represented by Western Welsh and Stagecoach, and these range from the 1960s to 1990s.
“So, lots of different travel experiences or memories for our visitors, plus they can see progress on our ongoing restoration projects inside The Bus Depot.
“We are always looking for volunteers who can spend a day a week in metalwork or those who have motor mechanic skills.
“It’s important for visitors to know we do not charge for travel, but donations are very welcome which are used to support our Welsh bus restoration projects”.
Three vehicles will return to service following repainting, repairs or full restoration, including one that has been off the road for 20 years.
A £2 route list will be available on the day.
