The 20-year-old died about six weeks ago in the Bahamian hospital where his mother gave birth just three days before, People Magazine reported Friday.
Anna Nicole's reported lover, Howard K. Stern, paid tribute to Daniel at Thursday's ceremony.
"Anna Nicole Smith laid her son to rest today," Stern said in the statement. "It was the most difficult day of her entire life."
The program included a message from Trimspa spokeswoman Anna Nicole, who said, "My dearest son Daniel, you were my rock, you were the only one that could keep me solid. Why God took you way from me I do not understand. Perhaps some day I will. It is so hard to think of you, but I do every second."
Daniel died on Sept. 10 while visiting his mother in the hospital after she gave birth to daughter Dannielynn Hope. Methadone, Zoloft and Lexapro were found in his system, reports said.