The popular event, run by the Wokingham Lions, takes place in the town centre, Elms Field and Erftstadt Court.
There will be a wide variety of entertainment including Maypole dancing, Morris dancing, ferret racing, a climbing wall, a ski slope and much more, between 10am and 5pm.
About 120 stalls will showcase their charities and organisations around the town for the 19th running of the fair. One of the organisers, Candy Kirkland, said: "We're all set for it and praying for good weather. We've got a good amount of stalls and individual fundraising events.There's lots going on and it's getting bigger and bigger.
What makes it special is the fact it's a community event and all the local schools and businesses get involved in it.
"It's one of the biggest events in Wokingham's calendar and perfect for family and friends."
Wokingham Town Mayor Councillor Peter Lucey will open the day on the main stage at 11am. Different types of music and dance will then play throughout the afternoon.
A children's fair will be set up in Elms Field with attractions including a bouncy castle, slide, and face painting.
Sue Balchin, another of the organisers, said the fair was a great chance for local businesses to encourage people to return to the town.
She said: "It's an opportunity for shopkeepers to capitalise and market their shops actively so people want to come back the next week." She added the Lions hope the event raises up to £30,000 for local charities.
The three featured charities this year are Wokingham & District Association for the Elderly (WADE), brain tumour charity the Ollie Young Foundation, and Wokingham & District Citizens Advice Bureau.
Part of Denmark Street will be closed during the activities.
Motorists can access the Denmark Street car park from Wellington Road.