Details on the photographer or when the portrait was taken were not immediately available.
"I am honoured to serve in the role of First Lady, and look forward to working on behalf of the American people over the coming years," Mrs Trump said.
The first lady lives in New York with the couple's 10-year-old son, Barron, and has largely remained out of the spotlight since her husband took office.
Former First Ladies Michelle Obama and Laura Bush also wore black in their official portraits
Mrs Trump and her son are expected to move into the White House after Barron finishes the school year.
She plans to focus on the problem of cyber-bullying among children, according to her biography on the White House website.
Mrs Trump, a native of Slovenia, is the second first lady to be born outside of the United States.
Louisa Adams, wife of former President John Quincy Adams, was born in London.
Former First Lady Hillary Clinton appears to wear black, too, in her official portrait, unveiled in 2004
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