The mother of one earned comparisons to Jackie Kennedy in the cashmere outfit, which featured a cropped jacket and knee-length dress.
Melania teamed the dress with matching suede gloves and powder blue court shoes. She wore her hair tied back in a bun and wore her signature dark eye make-up and a soft pink lip gloss.
It had been speculated for days that Melania would wear a Ralph Lauren design for the historic event, following her appearance in a one-shoulder jumpsuit from the American designer on election night.
"With the historic swearing-in of her husband, Donald J. Trump, as the 45th President of the United States, the First Lady-elect will become America's new first lady wearing an American designer who transformed American fashion, Ralph Lauren," her spokeswoman said in a statement reported by Women's Wear Daily.
The former model's outfit has drawn comparisons to the pale blue suit Jackie Kennedy wore for her husband John. F. Kennedy's inauguration in 1961.
It was a contrast to the glamorous sequinned Reem Acra gown Melania wore for the pre-inauguration candlelight dinner in Washington on Thursday evening. The 46-year-old gave us a glimpse at what we may be able to expect from her First Lady fashion choices in a gold embellished gown from the Lebanese-born, New York-based designer.
Despite some fashion designers publicly stating that they refused to dress Melania, the new First Lady has received support from a number of other designers, including Ralph Lauren, Dolce & Gabbana and Tommy Hilfiger.
Addressing the issue, Tommy admitted he doesn't think fashion designers should be swayed by politics.
"I think Melania is a very beautiful woman, and I think any designer should be proud to dress her," the designer told WWD. "Ivanka [Trump] is equally as beautiful and smart, although she wears her own clothes. I don't think people should become political about it."