Alexander Gwillym, 39, of Llantarnam, Cwmbran, sold the repackaged Asda chocolate bars as the Nestle brand from his shop in Cwmbran, Torfaen.
He and his firm admitted eight consumer protection charges to Newport magistrates and were ordered to pay a total of £1,880 in fines and costs.
The court heard Gwillym had tried to lodge his own "Mr Wonka Bar" trademark.
Magistrates were told Torfaen council trading standards officers had previously warned the defendant about his actions after he began selling the fake branded bars in September 2012.
An investigation found his store, Sweet66 Ltd in Cwmbran Shopping Centre, was selling repackaged Smart Price chocolate bars available from Asda.
The sweet shop firm was fined £400 and asked to pay £1,000 towards the prosecutions costs.
Company director Gwillym was fined £400 with an additional £80 victim surcharge.
The defendant had been told his bid to register a Mr Wonka Bar trademark was too similar to Nestle's Wonka trademarks and was likely to mislead the public, the court heard.
After the hearing, Torfaen councillor Gwyneira Clark, executive member for housing, planning and public protection, said: "Consumers expect to buy goods, including food, that are correctly labelled in accordance with consumer protection laws.
"The work of Torfaen's public protection service is vital to safeguard the health and economic well-being of the public and this prosecution sends out a message to all retailers that selling counterfeit goods will not be tolerated."
A shopkeeper duped customers by selling 30p supermarket chocolates as £3 Wonka bars, a court has heard.