According to the Broward County Sheriff's Office, the written note said there was a bomb aboard the Spirit Airlines flight preparing to take off Saturday night from Fort Lauderdale-Hollywood International Airport.
The sheriff's office swept the plane after getting the call around 10 p.m., but nothing was found.
Sheriff's spokeswoman Keyla Concepcion says authorities have to check out all threats.
The Atlanta-bound plane was taxiing when the note was discovered. A Spirit spokeswoman didn't immediately answer a question about how many passengers were on the plane.