The vessels were withdrawn from service in December so a review into safety could take place.
But new agreements have now been reached with Guernsey Coastguard. Crews have undergone further training and the vessels have been updated.
SJARS chief officer Jon Beausire welcomed the news that the two vessels were back in the water.
'I am pleased to confirm that the St John inshore rescue boats have been refitted and the volunteer crews have completed their extended training course to the satisfaction of Guernsey Coastguard,' he said.
'They are now able to resume the valuable service they provide to the Bailiwick of Guernsey.'
Sixteen volunteers have taken various Royal Yachting Association courses following the review, such as sea survival, first aid at sea and a marine radio course.
Six senior members of the team also underwent RNLI training to become helmsman for the vessels.
