Gosport Borough Council says it brought in the £100 fines to combat dog mess and poorly controlled dogs.
Previously walkers were allowed to walk up-to six charges, but this has been curbed with the new Public Spaces Protection Order (PSPO).
One professional dog walker said it will affect business.
Nick Lower, who runs Gosport Dog Walking, said: "There are a few professional dog walkers who are going to be affected, and members of the public as well."
Sue McNaughton, who will now have to walk her five huskies in two packs said: "I understand where [the council] are coming from, but they're penalising the many because of the few.
"I wouldn't walk five dogs if I didn't think I could control them."
Councillor Graham Burgess said: "In a densely-populated borough like Gosport, we do believe new rules are needed."
Some residents are happy about the change, including Jenny Brown who said: "I'm pleased this has come into focus. I've had so many problems when encountering larger groups of dogs."
Similar fines are in place in other areas including Oxford.
In 2011 the council brought in fines for people walking more than four dogs after complaints of packs being out of control.
Councillor John Tanner said: "With more than four dogs, you are not taking your dog out for a walk but a pack of potentially dangerous animals for a riot around the park."
Fines for people who walk more than four dogs at a time have come into force in a Hampshire town.