Mighty River Power has extended chief executive Doug Heffernan's tenure to cover the full 2014 financial results.
The state-owned energy company is set to be partially listed before the Budget in May.
Dr Heffernan has been at the helm of the company since it was formed in 1998 and will stay until the end of August next year.
Mighty River Power chair Joan Withers said the extension provides the company with certainty and the ability to plan for the succession process.
She said the firm was fortunate Dr Heffernan had committed to staying on to cover a period in which the organisation's performance will be subject to a lot of scrutiny.