Various Trump family members lined the steps of the White House following a private service that was held.
Robert Trump, the younger brother of the president and a businessman who avoided the spotlight, died on Saturday night, a day after the president visited him in a New York hospital.
President Trump announced the death in a statement.
"It is with heavy heart I share that my wonderful brother, Robert, peacefully passed away tonight. He was not just my brother, he was my best friend," the president said.
Robert Trump, who at 71 was younger than the 74-year-old president, was a business executive and real estate developer.