The funeral for Thatcher, who died Monday of a stroke, will be held April 17 at St. Paul's Cathedral in London.
Harper's spokesman tweeted the news Tuesday afternoon.
"Former [prime minister Brian] Mulroney has been invited to be a part of the Canadian delegation," Andrew MacDougall said on the social media site.
Thatcher is revered by many Conservative officials. In a statement Monday, Harper spoke glowingly of Thatcher's contribution to conservatism.
On Tuesday, the prime minister signed a book of condolences for Thatcher at the British High Commission.
"Canada deeply mourns the passing of Margaret Thatcher, a great friend of our country. Hers was a leadership example for the ages, from which we all benefit to this day — and will for many more to come," he wrote.
Buckingham Palace announced Wednesday that Queen Elizabeth and Prince Philip will attend the ceremonial funeral on April 17. It is the first time the Queen has attended a funeral for one of her former prime ministers since Winston Churchill's in 1965.