The passenger, who was on board a P&O Cruise, died from their injuries after being involved in the accident in Dominica on Wednesday lunchtime, a spokeswoman for the company said.
The bus, which was operated by a shore excursion provider, was carrying 12 passengers - including 10 guests from the cruise ship - at the time of the collision.
The majority of those injured have now been discharged from a local hospital, the spokeswoman said.
The passengers were travelling on the cruise ship Azura, which departed from Southampton in the UK on 28 October for a 14-night trip.
More than 3,000 guests and almost 1,200 crew are on board.
The passengers involved in the incident have not yet been named and representatives of P&O Cruises remain on site at the hospital to support those injured.
Paul Ludlow, senior vice president of P&O Cruises, said: “Our thoughts and prayers go out to everyone touched by this tragic event.
“Our employees and crew are working to do everything we can to extend support and assistance to those affected and their loved ones.”
P&O Cruises said it was “working closely” with local authorities, adding that the safety and well-being of guests and crew was “the absolute priority” for the company.
A Foreign Office spokesman said: “Our thoughts are with all those affected by this tragic incident.
“Our staff are providing support and we will remain in close contact with P&O Cruises and the local authorities.”