Thanks to tips and investigative work, authorities were able to watch a man and stop him while he was driving in the city in the early hours of Saturday morning, Stockton Police Chief Stanley McFadden said, Reuters reported.
The man, who was clad in dark clothing, had a mask around his neck and was in possession of a firearm when investigators stopped him, was "on a mission to kill," McFadden said at a news conference.
"We are sure we stopped another killing," he added.
McFadden identified the suspect as Wesley Brownlee, 43.
The shootings, which started last year and continued into September, have been linked by forensic ballistics evidence, authorities said earlier this month.
The San Joaquin County District Attorney's office was reviewing the evidence and the suspect will appear in court on Tuesday, said Tori Verber Salazar, the county's district attorney.
Six victims were killed, all but one in the Stockton area, and a seventh person survived her injuries.
On Oct 4, police released a surveillance video of a person of interest in the killing spree, and said the crimes could be the work of a serial killer "on a mission", although no motive was given.
Stockton is a city of more than 300,000 people in California's central valley, about 60 miles east of San Francisco.