Travelling to Capitol Hill in a different motorcade, Melania was welcomed with a standing ovation.
The appearance comes after the First Lady abruptly cancelled a planned trip to Davos, Switzerland, with President Trump last week, amid allegations that he had an affair with adult star Stormy Daniels.
The White House has quashed the rumours of the President and First Lady's marital troubles, blaming the separate motorcades on logistics and the latter wanting to spend more time with her guests.
According to a White House official, the Trumps will go together in the same vehicle to return to the White House.
Talking about the matter, Stephanie Grisham, a spokeswoman of the First Lady said, "Mrs. Trump is honoring her guests for the true heroes they are. In addition to holding a White House reception and photo opportunity for them and their friends and family, she is accompanying them to the Capitol".
Melania Trump wore a white Dior pant suit and nude Christian Louboutin pumps for the big occasion.
Trump observers quickly took to social media to note that white is a colour associated with the suffragette movement.
Melania wrote, "I will be joined tonight by an honorable group of Americans. Sitting with me are heroes who have served our nation in times of need, families who have suffered at the hands of evil, and citizens who have embraced the American dream".
Daniels, whose real name is Stephanie Clifford, divulged details about her alleged relationship with Trump during a 2011 interview with In Touch Weekly, which never ran until January 17 of this year.
The adult film actress said she and the billionaire businessman first hooked up in 2006, at a Nevada hotel outside of Lake Tahoe, and continued to see each other through 2007.
The interview was reportedly conducted along with a lie-detector test. (ANI)