Nadon fills the vacancy left by the mandatory retirement of former justice Morris Fish in August.
The new justice appeared before a parliamentary committee this week after his nomination by the prime minister.
Nadon was a justice of the Federal Court of Appeal when he was nominated to the high court.
Before that, he was a Federal Court judge, a judge of the Court Martial Appeal Court of Canada and a judicial member of the Competition Tribunal.
He is a recognized authority on maritime law.
Harper said Nadon came highly recommended.
"Mr. Justice Nadon’s remarkable knowledge of both common and civil law and his wealth of experience as a lawyer, a judge and an arbitrator make him highly qualified to join the illustrious ranks of the Supreme Court of Canada," Harper said in a statement.
"I have every confidence that he will serve with distinction and honour."