The former first lady pointed out that she was last in the Rotunda nearly five years ago to the day when the former president lay in state, his casket draped with an American flag.
The statue cast Reagan flashing his legendary ah-shucks grin, the expression that transformed his face whenever he was ready to deliver the punchline of a joke.
The sculptor, Chas Fagan, embroidered the top of the statue's base with chips of the Berlin Wall that ran around the perimeter.
The president's statue has a chocolate tone. It looms across a foyer from a likeness of President Dwight Eisenhower and is next to a painting marking Christopher Columbus's landing in the West Indies in 1492.
Former House Speaker Dennis Hastert, R-Ill., former Minority Leader Bob Michel, R-Ill., and Reagan-era White House Correspondent Sam Donaldson of ABC gathered in the Rotunda to see the unveiling.
Former Reagan Chief of Staff James Baker told a crowd that Reagan's statue now "will stand forever as a silent symbol to inspire."
One of Reagan's hands rests on a shelf, emblazoned with a torch. The presidential seal is embossed on one side of the base. The California state seal adorns the other. A quote from the 40th president is inscribed on the back: "America's best days are yet to come. Our proudest moments are yet to be. Our most glorious achievements just ahead."
House Speaker Nancy Pelosi, D-Calif., helped Reagan's 87-year-old wife to her feet to unveil the statue. With assistance, Reagan tugged back a blue drape cloaking the statue of her late husband. Mrs. Reagan called it "a wonderful likeness of Ronnie. He would have been so proud."
At the end of the ceremony, Pelosi and House Minority Leader John Boehner, R-Ohio, assisted Nancy Reagan off the stage. The crowd gave Mrs. Reagan a standing ovation as she prepared to leave. But before she exited, Reagan turned to wave good-bye, acknowledging the applause.
FOX News' Chad Pergram, FOX News Radio's Mike Majchrowitz and The Associated Press contributed to this report.