The EDL will protest in St George's Square, near the town hall, while the UAF will be demonstrating at Park Square on Saturday.
Police said the protests mean there will be disruption to the town centre from early in the morning.
The cost of the police operation is set to reach £800,000.
There will be severe traffic disruption in High Town Road, Midland Road, Mill Street and the bottom of New Bedford Road during most of the day.
Pubs and off licences will be open but will stop serving alcohol at midday until the protests have finished in the afternoon.
Chief Supt Mike Colbourne, divisional commander for Luton, said: "Uniformed officers from forces around the country are supporting Bedfordshire Police in policing this event so that everyone who comes into town on Saturday, whether a protester or a worker or a shopper, feels safe to get on with their day.
"Luton will look very different to normal, and there will be some traffic problems, but the officers, their dogs and horses are all there with the same purpose - to look after the town."