The Widnes-based builder has started construction of the Macmillan information and support centre at the Countess of Chester Hospital.
The new 688 sq ft single storey centre will be located in the grounds of the hospital and is due for completion in March 2011.
Whitfield & Brown said the centre will provide support and information to people affected by cancer in west Cheshire and Deeside, estimated around 250,000 people.
An official sod cutting attended by Ciaran Devane, chief executive of Macmillan Cancer Support, was carried out to mark the start of work.
Countess of Chester Hospital awarded Whitfield & Brown with a £165,000 contract to complete the construction of the building within 12 weeks. Synergy Architects designed the building.