Kevin Jones, 27, entered a plea of no contest to the charge as part of a deal with prosecutors. He had previously pleaded not guilty.
As part of deal, he will receive a maximum sentence of 30 days in the sheriff's work program.
Jones, a University of California at Berkeley journalism graduate student, was driving Halberstam to an interview on April 23 when the fatal accident happened in Menlo Park, south of San Francisco.
Based on witness accounts and an accident reconstruction, investigators determined that Jones made an illegal left turn into the path of a car that had a green light.
That car smashed into the passenger side of the vehicle where Halberstam was riding. Jones had a red light.
Halberstam, the author of 21 nonfiction books, won the Pulitzer Prize in 1964 for his coverage of the Vietnam War, a subject he revisited in his 1972 best-selling book, "The Best and the Brightest."