Arts Minister Tony Burke read out a message from the King, which said His Majesty was deeply saddened by the Australian comedian's 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 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.
Humphries was not only one of the funniest people in the world, he was also kind and generous, said Sir Elton John in a video message.
"He was a raconteur of incredible, incredible importance and genius, it's sad that we won't be seeing him again, but we have so many memories of him."
Rupert Murdoch, Sir Cameron Mackintosh, Andrew Lloyd Webber, Rick Stein, Rob Brydon and David Walliams were 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)
Film director Bruce Beresford told stories of making his first feature, The Adventures of Barry McKenzie, with Humphries and how in the early 1970s his friend struggled with alcoholism.
On one occasion Humphries ran from the pub to make it onstage after interval, said Beresford.
"He dashed into the wings and then onto the stage, the only problem was it was in the wrong theatre, in the wrong play."
Barry Humphries was a role model for Australians in ways he had never intended, Rupert Murdoch said in a video.
Sir Les Patterson was an example of how not to act when abroad, while Dame Edna showed the media giant that hair dye has its limitations.
"Barry you will never be silenced, your friendship still resides deeply in my heart," he said.
Humphries' daughter Tessa read out one of her father's poems, while sons Oscar and Rupert spoke on behalf of the family, thanking their stepmother Lizzy Spender.
Rupert recalled spending his childhood wishing he was with his dad, or following him on tour, hanging out in theatres, concert halls and TV studios.
"My favourite smell growing up was the acetone in his little pink pots of nail polish remover," Rupert said.
A musical interlude with the Australian Chamber Orchestra, cabaret performer Meow Meow and Finnish musician Satu Vanska, celebrated the songs of the Weimar Republic, which Humphries adored.
Among those in the audience were former prime ministers Malcolm Turnbull and John Howard, with prime minister Anthony Albanese giving a video tribute.
The service was hosted by television presenter Richard Wilkins, and ended with the audience singing along to a video Dame Edna's Why do we love Australia?
It was followed, of course, by a standing ovation.
Humphries delighted and outraged audiences for more than half a century with his cavalcade of grotesque alter-egos, 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)
Dame Edna, his biggest critical and popular success, would pick out "possums" from her audience and made them squirm, her appearances ending with a blizzard of "gladdies".
John Barry Humphries was born on February 17, 1934.
He continued touring up until the last year of his life and brought laughter to millions, even the King.
The sails of the Sydney Opera House will be lit up with an image of Dame Edna's sparkling glasses on Friday night.
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