Sheriff's spokesman Steve Whitmore says the 25-year-old was arrested late Tuesday during a traffic stop by Los Angeles police. He was booked on an outstanding warrant for driving without a license and released early Wednesday after posting $15,000 bail.
Court records show Stump failed to appear on a misdemeanor driving without a valid driver's license case in Beverly Hills in June 2007. A judge issued a warrant for his arrest at the time.
A phone message left for Stump's music publicist wasn't immediately returned Wednesday.
Fall Out Boy is scheduled to play at the Reading Festival in England on Friday.