John Gioia was first elected to the Contra Costa Board of Supervisors in 1998, after successfully challenging incumbent Jim Rogers, and has been re-elected six times.

[citation needed] He joined congressman then George Miller, Richmond city councilman Nat Bates and others in protesting the eviction of a popular pastor in 2010.

[6] Similar to the issue in 2010 in 2019 alongside congressman Mark DeSaulnier he urged a retirement home in San Pablo and its landlord to extend the stay for its many elderly residents.

[11] In 2003 Gioia joined Loni Hancock, Irma Anderson, and other area residents and politicians to protest and oppose the entry of Walmart into Hilltop Mall, however this was eventually unsuccessful.

[12] In 2005 he proposed banning new Indian Reservations and gambling institutions in the county and[13] also approved a measure to fine each supervisor $1 for every instance of bureaucratic mumbo jumbo.

[14] In 2017, the California Fair Political Practices Commission recommended a $14,000 fine for Gioia, levied for missed deadlines in filing multiple documents related to campaign contributions and expenditures.

[15] In 2018, Gioia traveled out of the country on a refinery junket to visit petroleum tar sands as a guest of oil companies.