The traditional double decker bus is kitted out with a kitchen facility and has an upstairs dining area for 32 people.
It will tour schools and businesses across the North of England, the Midlands and Wales to provide an 'extra special' dining experience to Mellors customers.
More than 1,000 pupils and teachers will have enjoyed a lunch experience by the end of June, hosted by bus driver Carol Regan.
Danielle Watkins, head of nutrition and food development at Mellors, said: “We’re constantly looking for cool new ways to engage with our customers. We aim to make the dining experience as fun as possible and the Mellors Big Red Bus is no exception.
“We’ve added an outside dining area complete with grass, picket fence and music to create a kind of festival vibe. Book the bus for 1, 2 or 3 days for a class treat, an extra serving point or a special occasion.”
Mellors operates over 270 catering contracts in education and business sites across the north of England, midlands and Wales.