The collision was reported at Bayfront Expressway and Marsh Road at 8:23 a.m., police said.
Officers arrived to find the injured bicyclist, a 33-year-old man, police said. He was taken to Stanford Hospital.
The driver of the vehicle, a 33-year-old Union City woman, remained at the scene and cooperated with investigators, police spokeswoman Nicole Acker said.
A preliminary investigation indicated that she was not under the influence of drugs or alcohol, according to police.
Westbound lanes of Bayfront Expressway were closed until 2 p.m. as police investigated the incident, Acker said.
Anyone with information about the collision is asked to call Menlo Park police at (650) 330-3600.