William and Kate paid their respects to fallen soldiers by attending the ANZAC day march and a commemorative service in Canberra before visiting the Australian War Memorial in the country's capital.
In the memorial garden the royal couple planted a 'Lone Pine', a tree specifically planted to honour the Australian and New Zealand soldiers who fought in Gallipoli 99 years ago, and laid a commemorative wreath.
CLICK ON PRINCE WILLIAM AND DUCHESS KATE PHOTOS FOR GALLERY
Prince William and Duchess Kate lay a wreath
"Used by HRH the Duchess of Cambridge on Anzac Day April 25, 2014, to plant a seedling propagated from the original lone in the grounds of the Australian War Memorial, which itself came from a pine cone sent back from an Australian soldier from the site of the battle at Lone Pine, Gallipoli," was engraved on the spade.
A similar one addressed Prince William's work.
The note on William and Kate's wreath, written by the Duke himself, read, "Never forget those who have paid the ultimate sacrifice for our freedom."
Afterwards, joined by Governor-General Sir Peter Cosgrove, Prime Minister Tony Abbott and the leader of the opposition Bill Shorten, the couple visited the Tomb of the Unknown Australian Soldier where they laid posies.
Kate's posy, which was made up of rosemary and native Australian flowers including Kangaroo Paw, contained a handwritten note reading, "In every second of every day, you will be remembered for your courage and your bravery. Thank you for your sacrifice and for what you have done for us. For that, I am truly grateful."
Duchess Kate got stuck into planting a tree
For the formal occasion Kate sported a blue and white Emillia Wickstead coat, navy heels and a dark navy pillbox hat by Australian milliner Jonathan Howard.
The 32-year-old Duchess added a jewelled poppy badge to her coat, while her husband Prince William wore a smart navy suit.
The Duke and Duchess of Cambridge place a poppy on The Roll of Honour for Anzac Day on their final day in Australia. pic.twitter.com/wZefaKDK5u
Earlier in the day the couple had made an unscheduled appearance at a 5:30am memorial service, for which they both wore black.
Given the earlier hour, Kate wrapped up against the cold in a quilted black coat and a cream scarf as she and Prince William took part in a pre-dawn solemn ceremony.
Prince William and Kate during their surprise earlier appearance
William and Kate's engagement at the war memorial marked the end of their three-week royal tour and the couple later boarded a Royal Australian Air Force aircraft as they began the long journey back to London.
Special spades were used by Prince William and Duchess Kate