Forever New was founded in Melbourne in 2006 by Dipendra Goenka who saw a gap in the market for women's occasion wear. Its first New Zealand store opened in 2010 and now has a total of eight.
Mackenzie said the High St store, which features a new style concept, was performing above expectations.
"The opening of our High St location has enabled Forever New to engage with a new corporate customer who has been asking for a city destination of the brand," she said.
"Our focus in 2018 will be developing the growth of our online channel."
Forever New would not disclose who its biggest competitor was.
Heart of the City chief executive Viv Beck said the opening of Forever New's only Auckland Central store was great for the local economy.
"It's really positive that globally successful brands such as Forever New choose the city centre to locate their business – contributing to our diverse retail offering," Beck said. "We continue to hear from retailers that high footfall due to growing number of people living and working here as well as the transformation of our public spaces are some of the key reasons why they want to come to areas such as the High Street District."
Pedestrian numbers on High Street are close to 10,000 daily.
Forever New has 290 stores across ten countries worldwide.