Tom Marsters, the Cook Islands Queen's Representative, and his wife Tuaine, are on their way to Buckingham Palace where he will be knighted.
The couple will also attend a war memorial service in Belgium for Cook Islands and Commonwealth soldiers.
Sir Tom, who was born on Palmerston Island, was a public servant before becoming an MP in 1991.
He held the seat until 2013 by which time he had become deputy prime minister and foreign minister.
Sir Tom resigned to become Queens Representative, a post to which he was re-appointed in 2016.