Robert’s service is the first White House funeral since 1963, where president John F Kennedy died from an assassination. The US president held the private event on Friday afternoon, with “several dozen” guests and his wife Melania Trump.
Mr and Mrs Trump accompanied the casket as it made its way from the White House to a hearse.
The funeral service was held in the East Room of the White House.
Mr Trump previously said he believed his brother would be “greatly honoured” by having a funeral at the White House.
He said to reporters on Friday: “He loved our country so much.
“He was so proud of what we were doing and what we are doing for our country.”
READ MORE: Trump dead: US President’s brother and ‘best friend’ Robert dies in hospital aged 72
Robert Trump died at 71 years old from an illness not disclosed to the public.
But sources close to the Trump family told to the New York Times he had suffered brain bleeds that began after a recent fall.
The US president dropped everything to visit his younger brother before he died.
Mr Trump flew to New York last week, where his brother died one day after the visit.
The White House funeral for Robert Trump was a rare occurrence, with Mr Kennedy’s funeral being the last service held at the government building.
Other presidents who were assassinated had services at the White House, including Abraham Lincoln and William McKinley.
Robert Trump is also one of only of a few private citizens to receive a rare funeral service at the White House.
The last private citizen to have a service there was Louis Howe in 1936.
Mr Trump refused to speak to reporters after the service, but said on Twitter: “Robert, I love you. Rest in peace!”
He also said in a statement on Saturday his brother was his “best friend” and that the two “will meet again”.
Speaking to Fox & Friends on Monday, the US president said his brother was his “biggest fan”.
He added: “When I became president, he was, I think, one of the most loyal people.
“There was no jealously… There was not an ounce of jealousy.”