The three other executives who resigned included Antoinette Campbell (in April), Jon Kingsford (in May), and Adele Henderson (in June).
It led to current councillor and mayoral candidate Nigel Simpson claiming the council "has a serious culture and leadership issue".
He said it was going to be a big decision around who to appoint as the next CEO.
In a statement on Wednesday, the council confirmed Rotarangi would not be returning prior to the end of her notice period.
"Elected members and the executive leadership team of Napier City Council are working together to ensure a robust plan is in place for the ongoing leadership of the organisation," the statement read.
"Currently, Debra Stewart, executive director infrastructure has taken on the role of acting chief executive through to September 12."