The event will see more than 30,000 people, representing over 200 countries, businesses, NGOs, and more, descending on the Scottish city.
The Queen was to host a major reception for world leaders at the global climate change summit, but Buckingham Palace confirmed on Tuesday that she will no longer attend.
A palace spokesperson said: “Following advice to rest, the Queen has been undertaking light duties at Windsor Castle.
“Her Majesty has regretfully decided that she will no longer travel to Glasgow to attend the evening reception of COP26 on Monday, 1 November.
“Her Majesty is disappointed not to attend the reception but will deliver an address to the assembled delegates via a recorded video message.”
It comes after the 95-year-old monarch underwent preliminary tests in hospital last week and stayed overnight at a medical facility for the first time in eight years.
She was advised to rest and carry out only light duties, and resumed virtual audiences on Tuesday.
Although the Queen will be absent, other senior members of the royal family are still expected to attend a series of events during the conference.
Which members of the royal family will be at COP26?
The Prince of Wales and the Duchess of Cornwall, as well as the Duke and Duchess of Cambridge, will be carrying out royal engagements from 1 to 5 November.
What will the Prince of Wales and the Duchess of Cornwall do at COP26?
Prince Charles, a long-time environmental campaigner, will reportedly address world leaders at the summit.
According to The Times, the UK government hopes that the prince’s presence will help secure a global deal that will renew commitments to limit global warming to 1.5C.
When Charles attended COP21 in Paris in 2015, he said there was “no greater threat to humanity” than climate change.
In a speech during the opening session of the conference, he said: “[Climate change] magnifies every hazard and tension of our existence.
“In damaging our climate we become the architects of our own destruction. While the planet can survive the scorching of the earth and the rising of the waters, the human race cannot.”
Ahead of COP26, Charles warned world leaders in a video message to the Saudi Green Initiative Forum in Riyadh that they have a “dangerously narrow window of opportunity” to avoid climate catastrophe and put the planet on a more sustainable path.
What will the Duke and Duchess of Cambridge do at COP26?
Prince William has joined his father in recent years in campaigning for more action to save the environment.
He launched the Earthshot Prize this year, which awarded a grant of £1 million each to five winners for their contributions to environmentalism.
Ahead of the award ceremony, he said in an interview for BBC Newscast that he feared the next generation would still be talking about climate change in the future.
“It shouldn’t be that there’s a third generation now coming along having to ramp it up even more,” he told presenter Adam Fleming.
“And you know, for me, it would be an absolute disaster if George is sat here talking to you or your successor, Adam, you know in like 30 years’ time, whatever, still saying the same thing, because by then we will be too late.”
It has not been confirmed if the duke or duchess will make any addresses at the conference.
What has the Queen said about climate change?
Earlier this month, the monarch appeared to suggest she was irritated by people who “talk” but “don’t do” anything about climate change.
Video clips featuring the Queen’s conversation during the opening of the Welsh parliament, appeared to show Her Majesty saying: “I’ve been hearing all about COP… I still don’t know who’s coming.”
“We only know about people who are not coming… It’s really irritating when they talk, but they don’t do,” she added.