The work begins next month at the Wetherby Road site which hosts the eponymous show for three days every July.
This year’s event is the 150th staging of the show which celebrates agricultural and country life.
Houseman & Falshaw, which is based in Copgrove to the north of the spa town, will build offices, a café and shop for the Yorkshire Agricultural Society.
The building will be constructed from a timber frame. The scheme has been designed by P+HS Architects.