City of Cardiff Council yesterday granted full planning permission for developer Signature Living to convert the 19th century Coal Exchange into a 200-bed hotel.
According to a planning report, heritage body the Victorian Society objected to the scheme, describing drawings as "unconvincing" and the level of detail in the application as "unacceptable".
But the report said that the application was only to establish the principle of using the building as a hotel.
Council officers pointed out that any plans to modify the inside of the building to accommodate services would still require listed building consent and that any changes to the exterior would need further planning permission.
The planning report said that, subject to certain considerations, the council's local plan favours hotel development in the Bay Business Area, where the Coal Exchange is located.
The report concluded that planning permission should be granted for the change of use "subject to such conditions as are appropriate and necessary to enable such a use in the given context".
Built in the 1880s, the Coal Exchange was was key to the success of Cardiff's booming coal trade. It became an events venue but was closed in 2013.