[2] Approaching his term limit at the end of 2012, he ran for and was elected to the Santa Clara County Board of Supervisors.

Simitian was one of only four Democratic Senators to vote against California's ambitious High Speed Rail plan.

[6][7] Azerbaijan's Foreign Ministry has put Simitian on a list of individuals banned from entering the country.

[8] Simitian was elected again to the District 5 seat of the Board of Supervisors in 2012, after reaching his term limit in the State Senate.

In 2022, redistricting adjusted the cities Simitian represents to include Los Gatos and Monte Sereno.

Under his guidance, Santa Clara County became "one of the first in the country" to hire a privacy specialist in a designated role to oversee its data-driven programs.

[18] In 2024, Simitian ran to represent California's 16th congressional district to replace the retiring Anna Eshoo, earning her endorsement in the primary.

"[27] At the conclusion of the recount, Simitian was ultimately eliminated and Low advanced to the general election by a 5-vote margin.