The US president arrived to thunderous applause at the UFC-316 mixed martial arts event, at the Prudential Centre in Newark, New Jersey on Saturday (local time).
Trump was joined by his daughter Ivanka Trump and her husband, Jared Kushner, along with son Eric Trump and Secretary of State Marco Rubio.
He also shook hands with the UFC broadcast team that included broadcaster Joe Rogan as fans wildly applauded and held up their phones to snap pictures.
The president appeared to be taking time off amid a second day of unrest in the Paramount district of LA.
Police, protesters clash in violent upheaval in LA
Demonstrations were sparked after at least 44 people were arrested by federal immigration agents when search warrants were executed at three locations.
A week of bitter back-and-forth led to Musk suggesting that Trump should be impeached, as well as claims that the government was concealing information about the president’s association with infamous paedophile Jeffrey Epstein.
Musk appeared by Saturday morning to have deleted his posts about Epstein.