In a statement, Transport for NSW said it did not encourage such experimentation.
Transport authorities said if the scientist is discovered using his implanted card, it could be deactivated.
“Customers that are caught tampering with their Opal card may have their card cancelled,” they said.
The implanted Opal card is not as sensitive as traditional cards and can require several swipes due to modifications including a shorter antenna.
“Changing the physical attributes of the card may impact the reliability of the Opal card,” Transport for NSW said.
Bio-hacker ‘not super stressed’
Mr Meow-Meow earlier said he hoped authorities would welcome his experimentation, because he believed they were open to innovation.
“Hopefully they react favourably and encourage this,” he told followers in a Facebook live event.
“I can walk out of my house, forget my wallet, forget my phone and everything and I’m still going to able to interact with technology.”
He acknowledged his chip might become obsolete in the coming years, but said he was “not super stressed” about it.
“Opal will be superseded in the next two to four years and I think [Melbourne’s] myki will too.”
Mr Meow-Meow’s Opal device was implanted by a piercing expert who could manage the risk of infection.
The bio-hacker warned others not to do the same without careful research and expertise.
He predicted NFC implants would grow in popularity and that companies could use them to give clients a more convenient experience.
“They’re going to say ‘Hey, do you want to give us your unique ID and then we’ll put that on and that will verify you?'” he said.