She provided inspiration and motivation that allowed him to recapture his love of painting and he has dedicated the exhibition, titled "Small Beginnings", to her.
Mrs Mackenzie was curator at the Forrester Gallery until her death after a short illness in July last year.
She had suggested he should have an exhibition but initially he did not want to.
When she died, he thought that would be the end of it, but then Forrester Gallery director Warwick Smith decided the exhibition would go ahead.
"I'd love her to see it," Mr Mackenzie said.
Born in London and raised in Brixton, he liked to paint and draw from an early age.
By 11, he had decided he would be a commercial artist, thinking he could combine his love for art with an income.
On his 15th birthday, he started work as a messenger boy for a major London commercial arts studio.
That began a career in graphic arts which took him around the world and to New Zealand, where he met his future wife.
But the pressures of the advertising world meant he had no time to indulge in personal art.
That opportunity came only after he retired and the couple moved to Lake Ohau.
With encouragement from Mrs Mackenzie, he painted in oils for the first time, describing the time of learning as "creative self-indulgence".
Having come from London and having spent most of his life in Auckland, to see the high country landscape, which was "so different" was exciting.
The most important thing was rediscovering the feeling he had as a boy.
The couple later shifted to Oamaru. The exhibition runs until February 13.
