Mr Marshall has been a committee member of Cruise NZ for more than 10 years and put his name forward to chair the organisation following an indication from outgoing chairman Craig Harris that he would not be seeking re-election.
Known as the "godfather" of the New Zealand cruise industry, Captain Harris has chaired the organisation for 20 years and was made a member of the New Zealand Order of Merit this year.
Mr Marshall said his role at the port and his involvement with Tourism Bay of Plenty had shown him the importance of the cruise industry in introducing New Zealand to foreign visitors.
"To me it's about the quality of the experience that people have here and New Zealand rates very highly worldwide for that quality so I'm just delighted to be part of something that has so much potential for New Zealand."
Mr Marshall said he intends to remain in Tauranga and make the most of his good health.
"I've had 36 years in the industry, first at the Port of Napier and then here. It's a major part of my life, so to leave it is a bit of a wrench but I'm also mindful of the fact that there's more beyond full-time work.
"I guess the real sadness about leaving is no longer being part of an exceptional company which has a fantastic future and being connected to a group of really, really great people who have established what is going to be a platform for huge growth in the future."
Acting Port of Tauranga chief executive Sara Lunam said the port was delighted to hear about Mr Marshall's new role.
"Graeme has always been a passionate advocate for the development of the cruise industry for the Bay of Plenty region and within our business.
"Graeme's drive has seen this business grow significantly to a point where there were 85 ship visits last season and we expect a similar number in the season ahead."
Tourism Bay of Plenty general manager Rhys Arrowsmith said the fact that Mr Marshall was unanimously voted to the chair's position was "a tribute to the respect he holds within the industry".
At Cruise NZ's annual conference on Monday, the Port of Tauranga was ranked in the top three ports in New Zealand for exceeding passenger expectations, he said.