Cantell, who has been with Fidelity for just over two years, will finish up in June. 

The company says she has left "an impressive legacy" which includes the acquisition of Westpac Life.

She is leaving to become the chief executive at Aon NZ. Cantell previously has spent more than five years in general insurance with IAG.

During her tenure at Fidelity the company has developed and launched a new tech platform and launched Career connect, a skills and training programme to grow the next generation of financial advisers.

With the acquisition of Westpac Life, Te Rūnanga o Ngāi Tahu (Ngāi Tahu Holdings) became a large shareholder.

On the product side Fidelity supporting customers dealing with cancer with its personalised Cancer companion programme.

In a statement Fidelity says: "Whilst it is disappointing to see Mel go, the board and the Fidelity Life team wish her well in this next stage of her career. The board will shortly commence a recruitment process to find our next CEO to lead us through the next phase of our journey.

"In the meantime, Fidelity Life is in a strong position and it’s very much business as usual. Our board, executive team and our people are united behind our purpose to give New Zealanders certainty to enjoy a more rewarding life, and are fully focussed on working with our partners and advisers to help more New Zealanders get the benefits of insurance protection."