McKenzie joined Telstra in 2004 and her most recent position at Australia's largest telco was chief operations officer responsible for field services, IT and network architecture and operations.
Institute of Directors governance leadership manager Felicity Caird said it was great to see McKenzie's appointment, but it was still concerning that just one out of the 50 top jobs went to a woman.
"I think some of the same drivers that have prevented women getting around the board table may apply for chief executives as well," she said.
"The statistics for the number of women in senior executive roles hovers around 20 per cent so we've got a very small pipeline coming through. So we actually need to focus more on that pipeline and having women in middle management and senior management. And we of course need to combat some of these natural biases when we go into the selection process."
Norah Barlow, former chief executive of Summerset Group Holdings Limited, was the last woman to head an NZX company before standing down last year.