Oscar E. Villegas was appointed by Governor Jerry Brown to the Yolo County Board of Supervisors, representing District One, on February 20, 2014, and was elected for a second term on November 8, 2016.  He was previously a continuous member of the West Sacramento City Council since 2000, and was re-elected to new terms in 2004, 2008 and 2012.  Fellow City Councilmembers also selected him to serve three terms as Mayor Pro Tem, most recently from 2009-2010.

Prior to his election to the City Council, Supervisor Villegas served as a member of the West Sacramento Planning Commission, dating back to a time when Bridgeway Island and Southport Town Center were mere drawings. He is also a strong advocate for the new Bridge District, a mixed-use downtown waterfront now under construction.

Supervisor Villegas has been a proponent of the City's Up for West Sacramento (UP4WS) Universal Preschool-early learning programs. He currently serves as Chair of the UP4WS Executive Board. He's also been a long term supporter of the new and expanded Arthur F. Turner Community Library, located near a revitalized West Capitol Avenue.

Supervisor Villegas has been employed by the Board of State and Community Corrections (BSCC) since 2008, and currently serves as a Field Representative with the Division of Standards and Training for Corrections.  Prior to joining CSA, Oscar spent two years as a Project Director of California's Access to Recovery Effort, a presidential initiative offering vouchers to youth for substance abuse services.

In 2003, Supervisor Villegas was appointed by the Governor to serve as Deputy Director of the Governor's Mentoring Partnership Program. While with the State Department of Alcohol and Drug Problems (ADP) between 2002 and 2003, Between 2002 and 2003, he managed the Office of Drug Court Programs. Supervisor Villegas spent nearly ten years regulating and investigating alcohol and drug treatment facilities throughout California with ADP.

Supervisor Villegas represents the County of Yolo by serving on the West Sacramento/Yolo County 2x2, the Sacramento-Yolo Port District Commission, the Sacramento County Regional Sanitation District Board, and the Capitol Corridor Joint Powers Board, Yolo County Housing, West Sacramento Redevelopment Successor Agency Oversight Board, Delta Protection Commission, Delta Counties Coalition and Sacramento Area Council of Government's Streetcar Policy Steering Committee.