The social media account of the former US President's son pumped out several prank and offensive posts, including that his dad had passed away.
The X (formerly Twitter) account of Donald Trump Jr. was apparently hacked on Wednesday.
A flurry of offensive and false tweets were posted at around 15:00 (GMT+3) on the profile of the ex-US President's son, which has more than 10 million followers.
They were all deleted shortly afterwards, some within minutes.
In one, Donald Trump Jr. - a right-wing political activist, businessman and author - announced his father had "passed away" and that he would be running for US president in 2024.
This tweet attracted 1.1 million views before being deleted.
In another tweet, Donald Trump's eldest son said North Korea, which has had historically tense relations with Washington, was about to "get smoked".
Though many users were quick to suggest that the posts were not genuine, inflammatory statements from well-known political figures can have serious risks.
Trump Jr. is vice president of the Trump Organization, a conglomerate of his father's business empire.
The 45-year-old was active in his father's failed presidential campaign in 2020, routinely hitting the headlines for making unfounded claims.
While his dad was president, Trump and his younger brother Eric controversially struck business deals and made investments with foreign countries.
Wednesday's incident could raise questions about account security at X, however it is not entirely uncommon for the accounts of high-profile individuals to be hacked.
It is unclear who is behind the apparent hack, with Donald Trump Jr. saying nothing as of yet on his personal, verified X account.
One of the tweets posted on Wednesday afternoon attacked Donald Trump's political rival US President Joe Biden.
"F**k @JoeBiden Stupid Ass N**a," it read.
Despite facing several criminal charges, Trump Sr. said in November he intends to run again for the White House, after being defeated by Biden last time around.
"We have to save our country," he said at the time.
After his father lost, Trump Jr. called for the results of the vote to be overturned, promoting a conspiratorial belief that the election was stolen.
During the apparent breach, Donland Trump Jr. posted he had some "interesting messages with Jeffrey Epstein," the US sex offender.
The 66-year-old, who committed suicide in prison in 2019, socialised with Donland Trump Sr. in the past, along with Bill Clinton and Prince Andrew.
It is unclear precisely what the believed hacker was alluding to.
Twitter has been rocked by instability since Elon Musk took over last year, with the US billionaire laying off many employees, reinstating previously banned accounts and overhauling content moderation.
In 2020, then Twitter suffered a major security breach that saw hackers take over accounts of major public figures, such as Barack Obama, Joe Biden and Musk himself.
Biden's son Hunter has been in the news recently, becoming the first child of a sitting president to get charged by the Justice Department in connection with a gun he purchased in 2018.