Lee McLaughlin, 19, from Inishowen, arrived in France on Sunday with his father and brother, and was due to fly back to Ireland on Tuesday.
They went to Ireland’s opening match against Sweden at the Stade de France on Monday evening before they returned to their hotel in Montmartre.
Mr McLaughlin is believed to have left the hotel before midday on Tuesday.
Garda Superintendent Gerry Delmar said officials and his family found him at Saint-Lazare metro station.
It is believed the missing man had texted another family member around 5am yesterday and a meeting was arranged with his family.
“He was found safe and well,” said Supt Delmar.
“They arranged a meeting with him at a Metro station. He got his phone working and they were able to make contact with him.
“He’s doing OK.”
The FAI had appealed to Irish fans in Paris to assist in the search for him.
His sister Rosemarie appealed to people on Facebook to find Lee on Tuesday evening.“This is very out of character for Lee... We are all very worried. Please please share my post and if anyone has seen him please contact any of his family ASAP.”