Justin Wayne Halstenberg, 34, was being held without bail. He is accused of igniting the blaze on Sept. 5 near Baseline Road in Highland.
Halstenberg was apprehended Tuesday after authorities obtained a search warrant at his home, authorities said at a Wednesday news conference.
"While we're still in the thrust of the preliminary investigation, we believe this was intentional," Sheriff Shannon Dicus told reporters. The motive for the alleged arson remained under investigation. Officials did not specify what was used to start the fire.
Man arrested for arson in connection with 34,000-acre Line Fire
A portion of Big Bear was placed under an evacuation order Tuesday as the fire continued to spread.
According to the sheriff's department, residents in the area from the Big Bear dam east to Wildrose Lane and the south shoreline south to Bluff Lake Basin were being told to leave. There was also an evacuation order issued for communities including Running Springs, Forest Falls, Angelus Oaks and Wrightwood.
The blaze blanketed the area with a thick cloud of dark smoke, which provided shade for firefighters trying to get ahead of winds expected later on Wednesday, said Fabian Herrera, a spokesperson for the Line Fire, which was 14% contained after burning 54 square miles.
Two of the main routes in and out of Big Bear - Highway 18 from the west and Highway 38 through the east - were both closed.
Interactive map from Cal Fire
This interactive map from Cal Fire shows the latest evacuation orders and warnings, plus road closures and detours:
This 3D map, also from Cal Fire, shows the breadth of the fire zone, and it includes the latest acreage.