In a speech before the Republican National Convention, she told the thousands gathered in Tampa, Florida, that her husband of more than 40 years "was not handed success. He built it."
"This man will not fail, this man will not let us down, this man will lift up America," Reuters quoted Ann Romney as saying.
She attempted to give voters a different glimpse of the former governor of Massachusetts, who's been seen by some as stiff and detached.
Ann Romney, 63, spoke of meeting Mitt at a high school dance and drew loud applause when she denied headlines boasting of a storybook marriage, declaring they have a "real marriage."
"In the storybooks I read, there were never long, long, rainy winter afternoons in a house with five boys screaming at once. And those storybooks never seemed to have chapters called MS or breast cancer," she said.
She also praised Mitt for overcoming challenges, helping revive the struggling Salt Lake City Olympics in 2002, and for helping her through her own battles with multiple sclerosis and breast cancer, according to The Associated Press.
In a surprise, Mitt Romney came out to hug and kiss his wife at the end of her speech. The walked off stage together to the Temptations song "My Girl."