The Royals started the day wreath-laying at the Australian War Memorial and bookended it with tree-planting at the Botanic Gardens.
The King and Queen were welcomed to the memorial by Governor-General Sam Mostyn and chair Kim Beazley before laying the wreath at the Tomb of the Unknown Australian Soldier during a rendition of the Last Post.
The King and Queen laid a wreath at the Australian War Memorial in Canberra. (Brook Mitchell/AAP PHOTOS)
Hundreds of well-wishers greeted them outside and upon their arrival at Parliament House, where they watched as they signed a set of official visitor books.
Indigenous senator Lidia Thorpe caused a stir during a reception in the building's Great Hall, protesting against the monarchy by loudly interrupting proceedings before being escorted outside.
But the ruckus did little to dampen proceedings, at which the King paid respects to Canberra's traditional owners and spoke of witnessing Australia's "sometimes difficult journey towards reconciliation".
"Throughout my life, Australia's First Nations peoples have done me the great honour of sharing so generously their stories and cultures," he said.
Senator Lidia Thorpe disrupted proceedings at a Parliamentary reception. (Lukas Coch/AAP PHOTOS)
Prime Minister Anthony Albanese and Opposition Leader Peter Dutton gave speeches about Australia's enduring relationship with the Commonwealth.
Mr Albanese spoke of a Commonwealth family that appreciated each other's differences and an Australia enriched by people from every culture while Mr Dutton lauded the monarchy as a bedrock of stability and democracy.
It was anything but a quick walkthrough for the King and Queen after the proceedings, with their Majesties talking to school kids and adoring fans for more than 30 minutes.
Commemorative crowns, bouquets and Australian flags and paraphernalia were plentiful but the day's best dressed went to Hephner the alpaca, who also got his opportunity to welcome the King before appearing to sneeze on the monarch.
King Charles chatted with owner of Hephner the alpaca while leaving the War Memorial. (Mark Baker/AAP PHOTOS)
Their Majesties briefly went their separate ways, with the Queen attending a discussion on family and domestic violence and the King meeting Mr Albanese and Mr Dutton at Government House.
King Charles was shown the Great Seal of Australia, used for important documents signed by the governor-general at Executive Council.
Acknowledging its importance, he joked it mustn't be dropped.
After the brief political firestorm at parliament, the King was off to witness a real one as the CSIRO's best scientists demonstrated how quickly a bushfire can spread in the Australian landscape and what was being done to tackle blazes.
The seven minute "Pyrotron" demonstration replicated a bushfire in a 29-metre long combustion wind tunnel before the climate-conscious King spoke with researchers about the challenges Australia faced because of its climate.
King Charles and scientist Matt Plucinski observed how quickly a bushfire can spread. (Tracey Nearmy/AAP PHOTOS)
Outside, an ACT Rural Fire Service engine doused itself during a "burn over drill", demonstrating how firefighters stuck inside in a firestorm would survive the worst of the inferno.
Despite the mist from the truck dampening the King's suit, his interest wasn't extinguished as he discussed what Australia was doing and how it could be applied in other countries.
Queen Camilla was joined by Domestic violence campaigner Rosie Batty, award-winning author Jess Hill and numerous advocates, experts and survivors for a roundtable discussion.
It's a subject that matters a great deal to the Queen who has worked to highlight organisations supporting sexual assault survivors for more than a decade.
The Royals strolled through the Rainforest Gully at the Australian National Botanic Gardens. (Mark Baker/AAP PHOTOS)
Joining back up at the Australian National Botanic Gardens, the time-honoured tradition of tree planting was obliged as the King and Queen were greeted by local school children who invited them to plant native seeds.
The pair planted a water gum in the Botanic Gardens to commemorate their visit, their last formal event in Canberra during this visit.
The royals will return to Sydney on Tuesday before going to Samoa to open the annual Commonwealth Heads of Government Meeting.
- with pool reporters
