More than 500,000 patients are treated by ambulance officers each year with over 80,000 being assessed and treated in the community without requiring transport to a hospital.
In these cases, the GP may not be aware of the call out and this information will help clinicians provide the best care possible for the patient.
St John National Patient Pathways manager Kris Gagliardi said people can be assured their information will remain private.
"Information will only be shared with patient permission, and not used for any purpose other than making informed decisions about their health care."
Gagliardi said it would substantially improve the continuity of care between ambulance staff and GPs.
"For instance, when an ambulance officer is called out to a patient with high blood pressure but no other symptoms, they can let the GP know that follow up and a possible review of medication is required."
"This will help a patient's GP team to be kept in the loop about ambulance call-outs and is a much-needed step in improving patient health outcomes."
She said an ambulance care summary will be sent electronically and includes details of the patient's clinical problem, any treatment administered, and care recommendations given to the patient.
"It is expected that electronic information sharing will be rolled out to the rest of New Zealand in the coming month."