David Morales, a house DJ and friend of Knuckles, attended Knuckles' memorial service shared a photo of the Obamas' condolence letter on Facebook.
"Frankie's work helped open minds and bring people together, blending genres to capture our attention and ignite our imagination," wrote the president and his wife. "He was a trailblazer in his field, and his legacy lives on in the city of Chicago and on dance floors across the globe."
Obama was on hand to declare August 25 "Frankie Knuckles Day" in Chicago back in 2004, when he was still a state senator in Illinois.
Swim Week Miami Beach 2014 [PHOTOS]