Swalwell was born in Sac City, Iowa and raised in Dublin, California. He graduated from Dublin High School in 1999.
He attended Campbell University in North Carolina on a soccer scholarship from 1999 to 2001. He lost the scholarship after suffering an injury. He then transferred to the University of Maryland, College Park. In 2003, he received a bachelor’s degree in Government and Politics at Maryland, and in 2006 earned his J.D. from the University of Maryland School of Law. He served on the College Park, Maryland city council as its student representative.
In 2014, Swalwell announced that he would serve as chairman of Maryland Governor Martin O’Malley’s O’ Say Can You See PAC’s Young Professionals Leadership Circle due to his friendship with the governor. He made clear that his support was about the 2014 midterm elections and not an endorsement of a potential presidential bid by O’Malley in 2016. However, Swalwell did ultimately endorse O’Malley in July 2015.