A four-metre tiger shark has bitten a kayak, sending a man "flying" into the water off the Sunshine Coast.

Surf Life Saving Queensland said the man was paddling about 1.5 kilometres off the headland at Moffat Beach when the shark knocked him out of his kayak on Thursday morning.

A man has had a lucky escape after a tiger shark knocked him out of his kayak on the Sunshine Coast. Credit:Blue Planet II

"Reports from the patient is an approximately 4.5-metre tiger shark slammed into his kayak and sent him flying into the water," a Surf Life Saving Queensland spokesman said.

"It apparently bit down on the kayak."