Six fire engines and around 40 firefighters were called to a boat alight at Trinity Buoy Wharf in Tower Hamlets.
The engine room in a catamaran passenger boat was destroyed by the fire. There were no reports of any injuries.
The Brigade was called at 1245 and the fire was under control by 1437. Fire crews from Poplar, Plaistow, Shadwell and surrounding fire stations attended as well as the fire boat from Lambeth River and partners from the RNLI and HM Coastguard.
The cause of the fire is under investigation.