The Lyft driver, described as a Middle Eastern man in his 30s from Sacramento, told the highway patrol he was taking the man home from a bar in Benecia about 1 a.m.
In Vallejo, the driver said, the passenger began to verbally and physically assault him on eastbound I-80 east of Tennessee Street.
When the driver stopped and got out of his car to get away, the passenger began to chase him on the right shoulder toward Redwood Parkway, the CHP said.
The passenger was struck in the far-right lane by a black Audi sedan driven by a Vallejo woman in her early 20s, according to the highway patrol.
"The Audi driver did not see the pedestrian until it was too late, and the Lyft driver only heard the crash," the CHP reported.