"It's like a brand new me," she said. "Sometimes I don't even recognize myself."
The award-winning singer and actress also spoke with Oprah about the murders of her mom, brother and 7-year-old nephew at their Chicago home in 2008. William Balfour, Hudson's estranged brother-in-law, was charged in their deaths.
"The only thing I can do to honor their memory is to make them proud," she said.
She said three things helped her through the tragedy: "my family, my baby and God." Hudson and fiance David Otunga had a son, David Jr., in August 2009.
The "American Idol" season three winner also performed her new single, "Where You At," during Thursday's episode. "I Remember Me" hits shelves March 22.