The former couple, who split in 2008, were in attendance at the teenager's birthday party and joined by their second son David, reported the Daily Mirror.
The family sang 'Happy Birthday' to Rocco and presented him with a cake during the celebrations.
Roco gave a speech at Ritchie's wedding to Jacqui Ainsley, with whom he has three children, Rafael, three, Rivka, two, and 13-month-old Levi.
The "Rebel Heart" hitmaker and the director, 46, married in December 2000, four months after the 56-year-old icon gave birth to Rocco John Ritchie.