She is currently on her annual trip to Balmoral and will be in Scotland for the reception on November 1.
COP26 president Alok Sharma tweeted that he was "absolutely delighted" that the Queen will attend the summit.
It is one of six engagements listed for the Queen on the official royal website, but it is understood the announcements made on Friday do not amount to her full autumn programme.
On October 2 she will attend the opening ceremony for the sixth session of the devolved Scottish Parliament alongside the Prince of Wales and Duchess of Cornwall.
Next up, and joined by the Earl of Wessex, she will launch The Queen’s Baton Relay for the Birmingham 2022 Commonwealth Games from the forecourt of Buckingham Palace on October 7.
A few days later on October 12, the Queen will be accompanied by the Princess Royal at a service of thanksgiving at Westminster Abbey to mark the centenary of the Royal British Legion.
On October 14, the Queen will attend the opening ceremony of the sixth session of the Senedd where, according to the Welsh Parliament’s website
She will be at Windsor Castle on October 19 where she will host a reception to mark the Global Investment Summit.
Despite currently being on holiday, work still continues for the Queen as every day she receives from Government ministers, and from her representatives in the Commonwealth and foreign countries, information in the form of policy papers, Cabinet documents and other state papers for her attention.