Marshall has also held a number of other senior interim roles, such as CEO of Grow Wellington, deputy CEO of NZQA, and deputy director of the Human Rights Commission.
"Transition periods between chief executives can sometimes be uncertain for all concerned," Marshall said.
"This is a great opportunity to be involved in helping the mayor and council through to having their new chief executive in place."
The council said it would work on appointing a permanent CEO, but that was not expected to be finalised until early 2021.
Wise added: "We are lucky to have someone as talented and experienced as Keith with us until then."
The mayor also expressed gratitude on behalf of the council to former CEO Neil Taylor, who stepped into the interim role at short notice.
"He has given so much to Napier over many years, and deserves recognition too for his commitment and efforts to see us through this response stage of the pandemic."