The Treaty Centre in Hounslow was evacuated as firefighters tackled a blaze at Debenhams on Wednesday (August 3).
More than 20 firefighters were called to the department store in Hounslow High Street where part of a storage room went up in flames.
London Fire Brigade said it was called to the scene at 11.42am and sent 21 firefighters in four fire engines.
Around 200 people left the shopping centre before the brigade arrived, and some 1,500 were evacuated from surrounding businesses.
The Treaty Centre reopened shortly after 1pm but the shopping centre said Debenhams would remain closed for the rest of the day.
The brigade said part of the storage room had been damaged, but the fire did not spread to the shop floor.
It said the cause of the fire was not known at this stage.
Yesterday (Tuesday, August 2), firefighters rescued three children and an adult from a house blaze in Harrow.
Paramedics from London Ambulance Service treated four patients and took them to hospital as a priority.