Mike Judge, from the service, said the cabinets would allow more people to access the vital equipment.
St John Ambulance have helped install more than 200 defibrillators in Jersey in the past 13 years.
The charity says moving them outside makes them available 24 hours a day.
A spokesman said dozens of islanders have been trained to use them and making them more easily accessible could help save more lives.
Mr Judge said the new cabinets are linked to the ambulance service and anyone can call 999 to request an access code.
He said: "We would urge owners of defibrillators to consider purchasing a cabinet and place it on the exterior of their building so that in the case of an emergency help can be given in the fastest time possible."
The first publicly accessible defibrillator was unveiled in May 2014 in memory of the former Commander of St John Ambulance Jersey, Nigel Truscott MBE.
It was placed on the outside of Morrier House in St Helier and since then another 13 have been placed on buildings across the island.
The charity says it wants to make Jersey a "heart friendly island" and the most heart aware place in Europe.
Micki Swift, from St John Ambulance, said: "With 220 machines being part of our St John Ambulance Jersey Defibrillator Programme that started in 2001 we are well on the way to reaching that goal.
"With so many people now trained by St John Ambulance to use this type of machine, I am sure these units will be greatly appreciated by the general public of Jersey."
Companies with a defibrillator should buy a cabinet and put it outside so it can be more easily reached, according to the Jersey ambulance service.