West Midlands Police launched an investigation after they were called to the Dickens Heath area of Solihull, where two parked cars suffered minor damage.
Aston Villa captain Grealish appeared to be pictured at the scene on social media following the incident.
Grealish had urged the public to stay at home just a day earlier after the Government last week enforced a lockdown and the midfielder has expressed his regret over failing to heed his own warning.
"Hi everybody. I just want to do a quick video message just to say how deeply embarrassed I am about what has happened this weekend." he said in a video posted on his Twitter account.
"I know it's a tough time for everyone at the moment, being locked indoors for so long and I obviously just got a call off a friend asking to go round to his. I stupidly agreed to do so.
"I don't want anyone to make the same mistake that I did, so obviously I urge everyone to stay at home and follow the rules and the guidelines of what we've been asked to do.
"I know for a fact that I'll be doing that in the near future now and obviously, like I said, I urge everyone to do the same.
"I hope everyone can accept my apology and we can move on from this, and hopefully obviously in the near future we can all be out enjoying ourselves again, once this has all boiled over. So cheers guys and thank you."
A Villa statement confirmed Grealish would receive a fine, with the money going to a local hospitals charity.
It read: "Aston Villa is deeply disappointed that one of our players ignored the Government's guidance on staying at home during the coronavirus crisis.
"Club captain Jack Grealish has accepted that his decision to leave his house was wrong and entirely unnecessary. It breached the government guidelines which are clear and should be adhered to by everybody.
"The player will be disciplined and fined with the proceeds donated to The University Hospitals Charity in Birmingham."