Police officer Jose Hernandez says the 32-year-old Johnson was arrested early Friday at the Bellagio. It wasn't clear if the 32-year-old woman received medical treatment.
Records show Johnson is being held at the Clark County jail on $15,000 bail.
Johnson starred for the Kansas City Chiefs, but most recently played for the Miami Dolphins in 2011.
He has been arrested several times during his nine-year NFL career.
Johnson was sentenced in March 2009 to two years' probation after pleading guilty to two disturbing the peace charges in separate incidents involving women at Kansas City nightclubs.