Motor Fuel Group has acquired Murco from Murphy Oil for an undisclosed sum.
The sale, which is expected to be completed by 30 September, brings to an end a sale process that has been ongoing for four years.
Motor Fuel Group currently has 60 sites, but the deal will see it add a further 228 company-owned forecourts and a more than 200 dealer network to its estate.
The forecourts will continue to operate under the Murco banner, and the shops under the Costcutter fascia.
“We are delighted with this exciting transaction,” said Motor Fuel Group managing director Jeremy Clarke.
“The signing of this agreement supports our stated objective to grow Motor Fuel Group into a significant force in the UK forecourt sector.”