In the letter, which appears to be handwritten, the pop star called Michelle Obama "the ULTIMATE example of a truly strong African American woman."
"No matter the pressure, and the stress of being under the microscope - she's humble, loving, and sincere," Beyonce wrote. "Michelle, thank you so much for every single thing that u do for us - I am proud to have my daughter grow up in a world where she has people like you to look up to."
It's not clear if Beyonce also mailed the note to the White House (her publicist did not immediately respond to ABCNews.com's request for comment).
Meanwhile, President Obama voiced his approval of Beyonce's husband in a new Atlantic article. Asked whether he prefers Kanye West or Jay-Z - the longtime collaborators headlined the Grammy-winning album "Watch theRead More »from Beyonce Pens Love Letter to Michelle Obama