More than 40 firefighters were involved in tackling a blaze last night at the former Barry Docks Conservative Club.
Officers from Barry, Penarth, Llantwit Major and Cardiff were drafted in to fight the fire which prompted the evacuation of neighbouring properties and the closure of nearby roads.
The fire broke out just after 8pm.
Extensive damage was caused to the derelict building but there no reports of any injuries. Nine hours later crews were still damping down.
Fire services advised residents in the area to keep windows and doors shut and remain away from the site.
The fire broke through the roof, but did not spread to other properties.
One family were evacuated from their home.
Lisa Down said she was at home when her six-year-old son came inside to tell her there was fire in the street.