In a solemn mood at Parliament House, the nation's leaders have paid their respects to Queen Elizabeth II while a group of school students huddled around a portrait of the late monarch.
Prime Minister Anthony Albanese could be seen writing in a condolence book on Friday morning.
"On behalf of the people of the Commonwealth of Australia, our sincere condolences on the passing of Her Majesty, Queen Elizabeth the Second," he wrote.
"Australia pays tribute to a life devoted to duty, family, faith and service that has brought such affection for Her Majesty over 70 years.
"We express our sincere condolences to the royal family."
Groups of visitors and school children lined the hall to witness Mr Albanese pay tribute.
Politicians from both sides lined up to offer their condolences and sign the book.
Liberal Senator Linda Reynolds, a former defence minister, tearfully spoke of her grief for the Queen.
"In my case, the Queen has always been a heroine to me in terms of her life of service and what she has delivered for our nation," she said as tears rolled down her cheeks.
"I was very proud to swear allegiance to the Queen as an army officer, then as a senator and also a minister.
"So I think she will be greatly missed and it's just a sad day for everybody."
Nationals Leader David Littleproud said he was shocked to wake up to the news.
"Deeply saddened, but grateful that during my lifetime, we've had a monarch that has reigned over us with dignity and with the respect of our nation," he told reporters.
The Queen opened Parliament House in May 1988, during one of her 16 trips to Australia.
Inside parliament's marble foyer, public condolence forms have been set up next to a portrait of the Queen.
Out front of parliament, a table has been set up for mourners to offer floral tributes.
Australian wattle bouquets have been laid, along with a bottle of beer and a can of gin.