The company, William Anelay, has been named as contractor on the £3.5m Key to the North project.
It will start on site at Pontefract Castle, Wakefield at the beginning on September.
Works will include carrying out conservation work to the monument that will take the castle off Historic England's 'At Risk' register.
The company will also restore and extend the Arts and Crafts barn to provide improved learning facilities, a shop, exhibition space and a cafe.
-- Advertisement --
The Key to the North project is funded by the Heritage Lottery Fund (HLF) which has awarded £3.04m, with other funding from Historic England, the council, the Wolfson Foundation and landfill charity EPaC.
Wakefield Councillor Les Shaw said: "We are pleased to announce the appointment of William Anelay Ltd as the contractor to carry out the capital part of this exciting project that will secure the future of the castle for future generations.
"They are well known for their work on historic sites and I'm sure they will carry out a first class job at Pontefract Castle."
Charles Anelay, William Anelay's Company Chairman, added: "Our workmen will be using a mixture of modern conservation methods, and traditional repairs to keep the feel of the Castle intact, and completely transforming the Barn as a new, modern visitor centre."
Work to remove trees from parts of the castle was carried out earlier this year in preparation for the main works.
(LM)
