The star and director of Jay and Silent Bob Strike Back boarded a Southwest Airlines plane from Oakland to Burbank, California at the weekend, but was furious when an air stewardess came over to share the captain's concern that he was a "safety risk".
In an angry post on his Twitter.com page, Smith writes, "I know I'm fat. But was (the flight captain) really justified in throwing me off a flight for which I was already seated?"
Southwest Airline rules stipulate that overweight passengers have to be able to "lower both armrests" at their seats - otherwise they must "proactively book the number of seats needed prior to travel".
Smith claims he was seated comfortably but was left red-faced when he was asked to leave after being recognised by several movie fans.
"I'm way fat. But I'm not THERE just yet. But if I am, why wait til my bag is up and I'm seated WITH ARM RESTS DOWN. In front of a packed plane with a bunch of folks who'd already I.d.ed (identified) me as Silent Bob."
Smith was offered a $100 (£62.50) airline voucher as compensation, but managed to board a later Southwest flight with no problems.