Bridgwater Carnival was traditionally held on a Thursday night
A shake-up of Somerset Guy Fawkes Carnivals will see Bridgwater Carnival move to a Saturday while Weston-super-Mare takes the vacant Friday slot.
Bridgwater decided to move days to try to attract more people.
North Petherton and Glastonbury will also take place on a Saturday while Wells will be held on a Friday.
It is hoped the changes, which will be introduced from 2012, will make it cheaper for the smaller carnivals' organising committees to work together.
NEW CARNIVAL DATES
Bridgwater: first Saturday after bonfire night
Weston: Following Friday
North Petherton: Second Saturday
Burnham: Following Monday
Shepton Mallet: Following Wednesday
Wells: Third Friday
Glastonbury: Third Saturday
Weston had battled it out with Burnham-on-Sea for the vacant Friday slot.
The chief marshall of Weston's Carnival, Jan Matthews, said: "It's a lot harder for mid-week carnivals to get funds.
"People work, people have children at school so the time it takes for people to travel to places means everybody would rather have a weekend event."
Bridgwater Carnival, which is the largest illuminated carnival in the world, attracts upwards of 100,000 people.
It dates back to 1605 when Guy Fawkes infamously tried to blow up the Houses of Parliament.
Traditionally it was held on a Thursday night but moved to the first Friday after Bonfire night in 2001.