In 2002, as Bordallo reached her term limit and as Delegate Robert Underwood vacated his seat and attempted to run for governor, she campaigned for and was elected as a Democrat to the House, serving from January 2003 to January 2019, and is the first woman to represent Guam in Congress. She was one of six non-voting delegates to the House of Representatives. While in Congress, she has devoted herself to economic issues and has helped to pass legislation that aids small businesses on Guam. She has also been involved in military and environmental issues.