The elder son of the US president posted the image of his daughter Chloe holding a bucket full of candy.
The caption read: "I’m going to take half of Chloe’s candy tonight & give it to some kid who sat at home. It’s never to early to teach her about socialism." [sic]
The tweet gathered 73,000 comments in less than 24 hours, including one from J.K. Rowling - the author of the Harry Potter series - who mocked Trump Jr's inherited wealth.
"Fill her bucket with old candy left by her great-grandfather, then explain that she has more because she's smarter than all the other kids," Rowling wrote.
There were several more tweets mocking Trump Jr's photo.

Donald Trump, Jr., son of US President Donald Trump, attends the 139th White House Easter Egg Roll on the South Lawn of the White House. Source: AFP
"Imagine thinking that teaching your child to share is bad," one wrote.
"Let me fix that for you... "Give some of the free candy she got to children who couldn't go out to get free candy," another wrote.
US President Donald Trump began his fortune when he built on his father's success in real estate.

J. K. Rowling attends the press preview of "Harry Potter & The Cursed Child" at Palace Theatre on July 30, 2016 in London, England. Source: Getty Images Europe