Swearengin was born in Texas and raised in Arkansas. Her family moved to Fresno in 1987. She graduated from Fresno Christian High School and California State University, Fresno.
Swearengin holds a Bachelor of Science (magna cum laude) and a Master of Business Administration (summa cum laude) from California State University, Fresno. Her husband, Paul, and she have two children, Sydney and Samuel.
In 2000, she became Director of the Office of Community and Economic Development at California State University, Fresno.
In 2002, she co-founded the Regional Jobs Initiative (RJI), an industry-focused effort aimed at helping the unemployment in Fresno County. She served as the Chief Operations Officer.
In 2005, she became lead executive for the California Partnership for the San Joaquin Valley, a group formed by Republican Governor Arnold Schwarzenegger. Today, she serves as the deputy chair of the Partnership’s board of directors.
In 2008, she ran for Mayor of Fresno, California. Swearengin campaigned on the four "priority issues" of Jobs and Education; Safe, Quality Neighborhoods; Effective and Responsive Government; and Regional Leadership. She defeated Henry T. Perea 54%-45%.
In 2012, she won re-election to a second term with 75% of the vote, defeating four other candidates.
In her first week in office, she and Police Chief Jerry Dyer introduced Operation Monitor: designed to allow GPS tracking devices on registered sex offenders after being released on parole. She inherited a difficult budget shortfall. She stated "I don't think anybody thought that within an 11 month window we'd have to close a $55 million dollar budget shortfall. When I started this job the general fund was $255 million dollars. So a $55 million dollar hole is significant for an organization of our size."
In March 2012, Ashley Swearengin announced that the City was facing a fiscal emergency because of the state's continued economic troubles combined with high cost contracts for certain segments of the city's labor force. A USA Today listed Fresno among 10 cities that could follow Stockton and Vallejo into Chapter 9 bankruptcy.
The unemployment level of the city of Fresno is 12.5%, and has fallen since Mayor Swearengin came into office. She proposed a plan called "Fresno's First Steps Home," which will battle chronic homelessness in the city.
In 2014, she ran for the California Controller's office, but lost to Betty Yee, 54-46.