Arts Minister Tony Burke read out the message from the King, which said His Majesty was deeply saddened by Barry Humphries' passing.
Those who shared the stage or screen with Humphries - or found Dame Edna at the back of a royal box - would recognise feeling fun and fear in combination, the message read.
Kathy Lette was among those at the memorial service for Barry Humphries at the Sydney Opera House. (Dean Lewins/AAP PHOTOS)
"Those who tried to stand on their dignity soon lost their footing."
"Those who wondered whether Australia's housewife superstar might this time just go too far, were always proved right."
Through his comic creations Humphries exposed pretensions, punctured pomposity, but most of all made us laugh at ourselves, the King wrote.
"Life really won't be the same without him. May our gladioli bloom in celebration of his memory."
The message was received with sustained applause, and followed by a video tribute from Prime Minister Anthony Albanese.
Sir Elton John, Rupert Murdoch, Sir Cameron Mackintosh, Andrew Lloyd Webber, David Walliams and Bruce Beresford, are also among those to offer their tributes.
Humphries entertained audiences in a unique blend of old-style music hall and contemporary satire. (Dean Lewins/AAP PHOTOS)
The comedy legend, best known for his alter egos Dame Edna Everage and Sir Les Patterson, died in Sydney on April 22 at the age of 89 following complications from surgery.
His death sparked an outpouring of tributes for the treasured national icon at home and abroad.
Humphries, who lived in London for decades, returned to Sydney in December 2022, where he suffered a fall requiring a hip replacement.
He died in St Vincent's Hospital as a result of complications following the operation.
Humphries delighted and outraged audiences for more than half a century with his cavalcade of grotesques, presented in a unique blend of old-style music hall and contemporary satire.
Barry Humphries attained huge success with alter egos Sir Les Patterson and Dame Edna Everage. (Joel Carrett/AAP PHOTOS)
Among them were the gross Sir Les Patterson, Australia's "cultural attache to the Court of St James", the melancholy and rambling Sandy Stone and, in comic strip and film, the chundering "Ocker in Pommyland", Barry McKenzie.
Bazza was a boozy parody of the ugly Australian abroad, full of phrases like the "technicolour yawn", "siphon the python" and "the one-eyed trouser snake".
Dame Edna picked out "possums" from her audience and made them squirm, her appearances ending with a blizzard of "gladdies"
She was a huge critical and popular success.
Humphries continued touring up until the last year of his life and was "an entertainer to his core" who brought laughter to millions.
John Barry Humphries was born on February 17, 1934.
The two-hour memorial event is being co-hosted by the Australian and NSW governments and is being broadcast live on ABC TV.
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