Walkers set off from Boulters Lock car park in Lower Cookham Road between 9am and 10.30am, crossing the river over Maidenhead bridge and following the river bank downstream.
After being ferried back across the river by sea cadets, the route takes them through Bray, Cox Green, Maidenhead Thicket and Pinkneys Green before returning to the start.
The walk is based on an old custom called Beating the Bounds, dating back to medieval times.
The route follows the line of stones installed to mark the town boundary in 1934 – although Maidenhead has now extended well beyond these.
Organiser Rotarian Jim Howles said the the Boundary Walk offers a ready-made fundraising opportunity for charities and community groups.
“Those taking part simply have to find sponsorship and walk the route,” he said.
“Join us this year to raise funds for your own charity, have fun, keep fit and make a difference.
“All of the organisation and administration is done by Rotarians including marking the route and manning road crossings, checkpoints and the base at Boulters Lock car park.”
About 400 people usually take part in the walk and, on average, the event raises £15,000 for a wide range of charities.
There is an entry fee to help cover the costs including first aid cover and insurance.
Taking part costs £3 per adult and 50p per child under the age of 12.
Registration for groups of 15 or more is just £10 if they sign up before Saturday, September 9.
There will also be a trophy for the group with the most walkers taking part.
For more information and to register for the event see www.boundarywalk.org.uk or you can email Jim at email@example.com or call him on 07731 522155.