Authorities say Jorge Arellano, 41, was arrested at his house at about 4:40 p.m. Wednesday.
The investigation began in October after detectives received a report of misconduct with an Oxnard High School student. Arellano was a teacher with the Oxnard Union High School District at the time of the alleged incident, police said.
It's unclear if Arellano is still employed with the school district. No further information was immediately available.
Anyone with information about the incident is urged to call the Oxnard Police Department at (805) 385-7605. Those who wish to remain anonymous can call Ventura County Crime Stoppers at (800) 222-8477.