It has been chosen to supply around 7,000 of its customers following a competitive process run by Ofgem.
The supplier will honour all outstanding credit balances, including money owed both to former and existing customers of Usio Energy.
Customers will be switched over to First Utility tomorrow and any credit on their account can be used to offset future energy use.
They will be contacted over the coming days and again in a few weeks when their accounts have been fully set up, at which point, customers wishing to change their tariff or supplier can do so.
Philippa Pickford, Interim Director at Ofgem said: “We are pleased to secure a deal with First Utility, where Usio Energy’s customers will be offered a competitive tariff for their energy. Their credit balances will be honoured and their energy supply will continue as normal.
“Our advice for customers of Usio Energy is to wait until First Utility contacts you. They will give you more information about the tariff you are on and about your credit balance if you have one. Then you can shop around for a better deal if you wish to.”