"It is unbelievable how we managed with what we had before," St John Cromwell area committee chairwoman Susan Dickie said.
An extension to the facility provides a new office, replacing one that was too small, and a crew room.
Other improvements include a new fully equipped sluice room to replace the single old laundry tub.
A donation of $7000 from the Cromwell Lions and Cromwell Golf Club allowed for furnishings such as a television to watch training videos.
Mrs Dickie said having somewhere the St John crew could get together "cements teamwork".
The extension was officially opened by Central Otago Mayor Tony Lepper and blessed by St John chaplain the Rev Libby Smith.
She also blessed the health shuttle service's van, donated by Four Square.
The free service was set up in Central Otago to help people get to appointments at Dunedin Hospital after St John staff saw how hard it was for some to travel to the hospital because of age or health-related issues.
With volunteer drivers, it runs Monday to Friday from Cromwell through either the Teviot Valley or Maniototo, depending on need.
Mrs Dickie said since the service started in January, more than 40 people had used it and about 24 people had signed up to be drivers.
St John began in Cromwell about 1941 and she said its workload had more than doubled, especially in recent years, so the next project would be an extension to the garage.
