The key will allow users to access Copilot, Microsoft’s AI tool, on new Windows 11 PCs.
Microsoft is a major investor in OpenAI, which powers Copilot’s AI capabilities.
It integrated AI into other products such as Microsoft 365 and Bing search in 2023.
Rival Apple has included a Siri button or option on its touch bar in Macbooks for a few years.
Copilot helps users with functions such as searching, writing emails and creating images.
In a blog announcing the change, Microsoft executive vice president Yusuf Mehdi said it was a “transformative” moment and compared it to the addition of the Windows key nearly 30 years ago.
He added that it would “simplify” and “amplify” user experience.
The new keyboards are expected to be on new products from February.
Microsoft will showcase some of the products with the Copilot key at the upcoming CES tech event, which starts next week in Las Vegas.
When Copilot was integrated into Office 365 products such as Word, PowerPoint and Teams, it could summarise meetings, write emails and create presentations.
It has also been added to search engine Bing.
The introduction of the button is a “natural step”, according to Prof John Tucker, computer scientist at the University of Swansea.
While Windows 11 users can already access Copilot by pressing the Windows key + C, he says the new key “shows the value the company is placing on this particular feature and its potential to draw and bind users to all their many products”.
But he added: “Of course, that the keyboard has changed so little in 30 years – since 1994 – is not something to be proud of.”
Google, by far the world’s biggest search engine, has its own AI system called Bard.
However, it was Microsoft’s partner OpenAI that introduced its powerful AI tool ChatGPT in 2022 which caused rivals to scramble to release their own versions.
Copilot is based on OpenAI’s GPT-4 large language model.
The UK’s competition watchdog is looking into Microsoft’s relationship with OpenAI after boardroom chaos resulted in a close relationship between the two firms.
