Dog owners in Prescot and Whiston face fines of up to £100 if they fail to carry poo bags to pick up after their pets.
It is part of a series of measures designed to promote responsible dog ownership following a public consultation on the introduction of public spaces protection orders.
Town hall chiefs at Knowsley Council have also brought in rules banned dogs from a number of childrens’ play areas and parks.
Dogs must also be kept on leads in all borough cemeteries.
The new order comes into force on Friday, October 20 follows a public consultation carried out by Knowsley Council between March and May this year.
Coun Eddie Connor, cabinet member for Neighbourhoods, said: "I’m pleased to announce the introduction of tough new restrictions against irresponsible dog owners in Knowsley.
“These measures received a huge amount of public support when we carried out a consultation earlier this year.
“We know from speaking to our residents – both those who own dogs and those who don’t – that tackling irresponsible dog ownership is an important issue in the borough.
“This order gives us additional enforcement powers to help us encourage responsible dog ownership and improve the quality, cleanliness and safety of our public spaces in Knowsley.”