After she was shown a short video, the Queen cut a Brooke anniversary cake and received a framed gift.
In a brief speech, she said: “Can I thank you all for your support – it [Brooke] is the most remarkable charity.”
Chris Wainwright, the chief executive of Brooke, said: “We are so lucky to have [the Queen’s] support. It means everything to our staff, the communities that we work in, our partners, and just having the support of someone as high profile as Her Majesty gives us the opportunity to engage with a whole different and wider audience.
“It shows that actually our cause is important, and that’s the main thing for us.”
Mr Wainwright added: “It’s a huge milestone for us, but to be recognised by Her Majesty and for her to host a reception for us, is fantastic for the people that make Brooke happen.”
The reception comes after the Queen also hosted the first garden party of the year with the King and other Royal family members at Buckingham Palace on Wednesday.