Part of the St Clement Coast Road was closed as crews tackled the blaze which started in a shed behind a shop at Green Island before spreading to nearby bushes and the main property.
Firefighters said they were met with a 'large fire' when they arrived at about 8.30pm, and locals reported seeing embers 'the size of plates' being blown around in the near-gale-force winds.
The occupants of the main property had already evacuated after seeing the smoke when they went out to investigate why their electricity supply had failed.
Watch Commander Mark Bailey-Walker said: 'By closing the door to the rear of the building they prevented a significant fire from developing into something much more serious – a simple action like this can make all the difference.'
The shed was destroyed and the gutters of the main property were melted and windows were broken.
Lindsay Greechan, who runs Your Store – the Green Island shop involved in the fire – posted on the 'Jersey Ask! Advise! Advertise!' Facebook page to thank Islanders for their support.
'Thank you for everyone's concern. The fire was detected quickly by staff and the family upstairs were evacuated within minutes – thankfully no one was hurt.
'The shop won’t be open as usual at 7am until we can have the all clear to do so. Thank you to the amazing fire brigade and police who acted so quickly and ensured the safety of everyone.'
An investigation is being carried out by the States police and the Fire and Rescue Service.