[6] Mills family moved to Dunedin in the South Island of New Zealand when she was a teenager, and she went on to study at Otago University.
Her thesis is: Benthic macrofauna assemblages of fragmented seagrass (Zostera capricorni) beds in two southern New Zealand inlets.
In 2006 Mills started work with National Institute of Water and Atmospheric Research Taihoro Nukurangi (NIWA).
This role heads a small team and is responsible for over 300,000 of preserved marine invertebrates specimens from around New Zealand, Antarctica and the South West Pacific.
Mills was the co-leader of the 2024 Ocean Census Bounty Trough research expedition.