The warden was accused of "bizarre behaviour" when he put the yellow sticky ticket envelope on the bin left on double yellow lines in Carmarthen town centre.
Carmarthenshire Council said no ticket was inside the wrapper and the incident was a light-hearted moment.
However it said the warden's conduct was being looked into.
Salesman Mike Jones said he spotted the warden talking to other motorists about the wheelie bin from a town centre shop blocking the road, the BBC reported.
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"It appeared the warden slapped the plastic ticket envelope on the bin in a moment of high jinks after a member of public pointed out it was parked on double yellow lines."
Carmarthenshire Council traffic and safety manager John McEvoy said: "There was no ticket issued, it is not possible to book a wheelie bin or anything that is not motorised.
"Although this was meant as a humorous incident, we take this kind of thing very seriously and have launched a formal investigation into the conduct of this officer."
"The ticket issued was simply a throw-away gesture and proved to be a load of rubbish. We are wheelie careful and do our best to make sure that our bins are in the correct locations at all times," he was quoted as saying by local media.