John Hollis has overseen both the charitable and the emergency ambulance sides of St John but leaves the role due to ill health.
St John say John Hollis' decision has been made with the support of his family and senior figures in the organisation, after a period of ill health.
He was appointed to the senior role, which provides leadership and oversight, in November 2022.
His career spanned international business and latterly a role advising government.
It was during his time with the States that Mr Hollis undertook a thorough review of St John.
Ambulance and Rescue CEO Mark Mapp says this was an important piece of work:
"His report was innovative, and many solutions to today’s healthcare challenges lie within his work and recommendations. John has been a strategic motivator and a driving force behind transformative changes, and his legacy will continue to inspire us all.”
His role in St John was also ceremonial and he was presented to their Majesties during their Royal Visit to Guernsey in July 2024.
The CEO of the St John Guernsey charity, Heather Langlois, says Mr Hollis was a role model:
“His ability to inspire teams, support ideas and lead change are skills that the Charity will benefit from for years to come. John perfectly embodies the Charity’s values of Humanity, Excellence, Accountability, Responsiveness and Teamwork, and during his time as Knight Commander he has ensured a more sustainable future for the Charity.
It will forever be one of my greatest privileges to have had the opportunity to learn from and work alongside John."
A process to select his successor will begin in the coming weeks.