Ms Swainson said to be promoted from a pool of people who gave so much of themselves was "extremely humbling".
"Most of us just do what we can and we don't think we do anything special. We just give what we can and hope it makes a difference," she said.
Ms Swainson began with St John as a cadet and attained her Grand Prior's Award. From there she moved on to become a volunteer ambulance officer at the Tauranga Station, often crewing on graveyard shifts.
She is also involved with the Tauranga/Mount Maunganui Area Committee as chairwoman and is an elected member of the Central Region Trust Board.
Mr McOnie has been involved with St John for more than 20 years and has fostered a strong relationship with the youth division.
Mr McOnie said he was shocked but humbled.
"I was surprised. It was a nice surprise but there are many more organisations and people.
"It's unfortunate that everyone can't be recognised.
"It's quite humbling for me," he said.
St John central region general manager Eddie Jackson said volunteers such as Ms Swainson and Mr McOnie were crucial to providing a full range of services, including ambulance services, first aid training, community care services and youth programmes.
"Our volunteers come from all walks of life, age groups and occupations but they all have one thing in common - a commitment to communities and to enhancing the health and well-being of New Zealanders," Mr Jackson said.
St John Honours are sanctioned by the Queen, as the Sovereign Head of St John.
They are awarded every year on merit to St John members, both volunteer and paid, who stand out from their peers.
The honours will be presented at awards ceremonies next year by the head of St John in New Zealand, Governor-General Sir Jerry Mateparae.