The visit will coincide with the Sydney Invictus Games in October.
Prince Harry and Meghan tied the knot on May 19.
Prince Harry and Meghan Markle at the 2017 Invictus Games in Toronto.
For the prestigious ceremony - which marks Queen Elizabeth II's 92nd birthday - was the flawless opportunity for the former actress to demonstrate her sartorial prowess and she didn't disappoint.
So far, it seems Meghan has impressed Queen Elizabeth.
Roughly 1,000 soldiers marched to House Guards Parade in Whitehall, central London, as part of the Trooping of the Colour ceremony.More news: 'Just incredible' as Nadal wins 11th French Open despite late injury scare
Buckingham Palace tweeted that she had only missed one such event during her reign, and that was in 1955 during the country's general strike.
As People reports, Duchess Meghan joined Harry, his brother William and wife Kate Middleton along with their children, Prince George and Princess Charlotte (little Prince Louis stayed home), in addition to Prince Philip, Prince Charles and Camilla, Duchess of Cornwall.
The couple postponed their honeymoon by several days to attend a garden party at Buckingham Palace in honor of Prince Charles three days after their spectacular wedding last month.
The first British royal to visit Australia was Prince Alfred, the son of Queen Victoria, in 1867 as part of his round-the-world voyage. Eugenie, 28, meanwhile, looked lovely in emerald green, also opting for statement headwear - with a pretty floral embroidered hat to complete her look.
While Harry and Meghan's premier tour has caused a buzz of excitement in the worldwide media, fears have been raised about the couple's desire to start a family as soon as possible.
"His attendance, alongside the Duchess of Sussex, will be a wonderful highlight for the more than 500 competitors and thousands of spectators", Mr Turnbull said. "They will go on, and good luck to them, long after we are a republic".