Jeff Hewitt

In an upset victory, Hewitt was elected to the Riverside County Board of Supervisors from District 5 in 2018 against former Republican Assemblyman Russ Bogh, despite Bogh raising twice as much money as Hewitt. Hewitt was sworn into office as a supervisor on January 8, 2019, by Libertarian National Committee Chair Nicholas Sarwark, succeeding retiring supervisor Marion Ashley. In 2018, the Los Angeles Times named Hewitt as the most powerful Libertarian ever elected in the United States, though according to Reason he has since been surpassed by Wyoming State Representative Marshall Burt.

Amid the California government response to the COVID-19 pandemic, Hewitt pushed Riverside County to reopen its businesses more quickly than the rest of California. In September 2020, Hewitt introduced legislation to establish restrictions specific to Riverside County, which would've been looser than those set by the state. The legislation would've allowed some indoor services that had been ordered closed to reopen with capacity limits, including restaurants, gyms, hair salons, places of worship, movie theaters, libraries, and retailers. Hewitt's proposal would have reopened the County fully by November 3, with large events being permitted starting on October 13. Due to a threat by Governor Gavin Newsom to cut state funding to counties that did not follow his guidelines for reopening, Hewitt's plan had the potential to cost Riverside County between $28 million and $656 million in state funding. Hewitt argued that the additional tax revenue gained from reopening the County would offset any loss of state funds. On September 22, the Board of Supervisors voted 3–2 to advance Hewitt's proposal, but delayed its implementation to October. On October 6, the Board voted 4–1 to enact a modified version of Hewitt's plan, with Hewitt as the sole opposing vote. Hewitt says he voted against the final version because the specific deadlines in his original proposal had been removed, and language had been added directing the County to cooperate with the state on reopening guidelines.

In November 2020, a female county employee filed a lawsuit against the county which accused Hewitt of sexual harassment back in May 2020. Riverside County settled the lawsuit in connection with the allegation for $50,000 in April 2021. Later that month, another female county employee filed suit against the county, and accused Hewitt and his chief of staff of making "disparaging and vulgar comments" back in October 2020.

On January 12, 2021, Hewitt was elected by the board to serve as its vice chair for the year. He succeeded Karen Spiegel, who was elected Chair. On January 12, 2022, Hewitt was elected by the board to serve as its chair for the year, with Kevin Jeffries elected Vice Chair. In an unusual move, supervisors Chuck Washington and V. Manuel Perez, both Democrats, abstained from voting on the 2022 appointments. Such votes have been unanimous for at least the last two decades, with the positions rotated annually by district. Washington has also endorsed Hewitt's 2022 re-election challenger, Democratic mayor Yxstian Gutierrez of Moreno Valley, potentially the first such endorsement by a sitting supervisor against a colleague. Hewitt and Gutierrez advanced from the top-two primary on June 7, 2022. Hewitt lost re-election to Gutierrez in the general election.

Hewitt sought election to the California State Senate in 2014 and the California State Assembly in 2016.

On April 2, 2016, Hewitt was elected the Region 4 representative to the Libertarian National Committee, succeeding Daniel Wiener. He was re-elected in 2018 and 2020. Hewitt announced his candidacy in the 2021 California gubernatorial recall election in an op-ed in the Orange County Register on May 2, 2021. The 50% threshold to recall incumbent Democrat Gavin Newsom was not reached. Hewitt received 0.7% of the replacement candidate vote.