His son, Grand Duke Henri revealed the news in a statement saying, “It is with great sadness that I inform you of the death of my beloved father, His Royal Highness Grand Duke Jean, who has passed away in peace, surrounded by the affection of his family.”
Jean is survived by five children - who he shared with wife Princess Josephine-Charlotte of Belgium who died in 2005 - 21 grandchildren and 15 great grandchildren.
The Duke made his last public appearance of February 16 to attend the funeral of his sister Princess Alix.
As a graduate of the Royal Military Academy of Sandhurst, the former monarch also took part in the D-Day landings and the liberation of Luxembourg from Nazi Germany.
And, in 2002, Jean abdicated the throne in favour of his son Henri after close to 36 years on the throne.
During his reign he helped transform Luxembourg into a centre for financial service.
The European commission president, Jean-Claude Juncker - who was one of Jean’s prime ministers - also released a statement after the news broke.
“Like all the people of Luxembourg, I had great esteem for this man of commitment, kindness and courage who, throughout his reign and in all circumstances, gave the best of himself to his country," he said.
“Grand Duke Jean has always been close to Luxembourgers who are today united in the same sadness.”