Revell said a quarter of the retail brands surveyed also failed to meet the requirements.
She said the biggest risk was for businesses that relied heavily on marketing directly to consumers and on bricks and mortar stores that used mobile searches to drive foot traffic.
"Retail is a particularly competitive industry and in the case of a shopping mall or district, mobile search driven foot traffic has become a key driver of sales," Revell said.
"Those sites which are mobile friendly can expect a significant boost in mobile search engine rankings, site traffic and potentially sales."
A number of high-profile international businesses had also reportedly failed the test, with Revell saying New Zealand was not alone in needing to prepare for the changes.
Google has an online test for webmasters to check their website's mobile capability here and tips on how they can make their sites more mobile-friendly.
An earlier version of this article incorrectly stated that websites which did not meet the requirements for mobile could be cut from Google's search engine.