Police say it is too early to say whether the unidentified "person of interest" is the same man shown on a video distributed Sunday.
Authorities distributed video at a news conference from a security camera that showed a white male in his late 20s to early 30s, dressed in black, with receding hair held in a ponytail. The Los Angeles Times reported that the man detained Monday was driving a blue minivan with Canadian license plates.
Los Angeles Police Commander Mike Moriarty said witness reports and video footage placed the man at several of the locations where fires were started.
Fire officials reported eight arson fires on New Year's Eve and early on Sunday and Monday, including five in Los Angeles, two in West Hollywood and another in nearby Burbank, bringing the number of suspicious blazes since Thursday in those areas to 55.
Firefighters also fought a blaze on Sunday in a large abandoned home in Hollywood, although it was not immediately clear if it was linked to the spate of arsons, many of which have started in cars before spreading to carports and homes.
Police spokesman Cleon Joseph urged residents to be on the lookout for anyone acting suspiciously.
"Keep your lights on, be diligent, watch your surroundings. If you see anything, call 911," Joseph said.
Los Angeles Police Department Commander Andrew Smith said dozens of detectives had worked through the night to gather evidence and sift through clues.
"We've reassigned dozens of detectives," Smith said. "Those detectives are now working together around the clock ... We've got hundreds of clues, dozens of witnesses, and countless pieces of evidence," he added.
So far, no one has been seriously hurt, but a firefighter was treated and released for injuries suffered at the site of one blaze over the weekend and another person suffered minor injuries on New Year's Eve.
One of the blazes damaged a house in the Hollywood Hills, where The Doors lead singer Jim Morrison was inspired to write the 1968 song "Love Street" about his girlfriend Pam Courson and what was then a hippie hangout.
Fire chiefs declined to say how the blazes were started.
(Editing by Cynthia Johnston)