Franceso Galdeli, 58, and Vanja Goffi, 45, were arrested by a joint operation of Interpol agents from Rome and Thai investigators, Thai police said.
The couple, dubbed the Italian Bonnie and Clyde, have been wanted on an Interpol red notice since 2013.
Galdeli was arrested on Saturday near the city of Pattaya on suspicion of staying in the country illegally, while his wife was arrested on suspicion for overstaying her visa.
Clooney sued them in a 2010 trial in Italy and testified against them, saying they had fraudulently used his name.
The Oscar winner said he never approved any affiliation with the bogus brand “GC Exclusive by George Clooney”.
“During interrogation, Francesco confessed to claiming to be George Clooney and opening a clothes business to trick people into sending money,” a statement from Thailand’s crime suppression division said.
They are also accused of various other scams and frauds in Italy, including selling fake Rolex watches online and sending packets of salt to customers instead.
The couple overstayed their visas and had been living in Thailand since 2014, according to authorities.
Police said the couple do not yet have a lawyer and will be charged for overstaying their visas before extradition proceedings begin.
They said Galdeli was sentenced by a Milan court in 2010 to serve more than eight years in jail after being found guilty of impersonating the actor to trick investors, but fled the country.
He was then arrested in July 2014 at Pattaya’s Dusit Thani Hotel but managed to escape a day later.
Local police discovered he had paid prison guards 20,000 Thai baht (ÂŁ500) to cover up his absconding, The Telegraph reported.
