Puigdemont defiantly appeared in Barcelona on Thursday after travelling from Belgium and made a speech in front of a large crowd of supporters.
He faces charges of embezzlement for his part in the attempt to break Catalonia away from the rest of Spain in 2017.
Puigdemont appeared in a central Barcelona park where several thousand separatist supporters who had gathered in expectation of his arrival waved Catalan flags.
He punched the air to cheers on a bright, sunny day.
Addressing the crowd, Puigdemont accused Spanish authorities of "a crackdown" on the Catalan separatist movement.
"For the last seven years we have been persecuted because we wanted to hear the voice of the Catalan people," Puigdemont said.
Supporters of Catalan independence leader Carles Puigdemont wait for his arrival in Barcelona. (AP PHOTO)
"They have made being Catalan into something suspicious.
"All people have the right to self-determination."
After his speech, Puigdemont went into an adjacent marquee tent.
There, he hurried out of an exit and jumped into a waiting car that sped away, according to an Associated Press photographer who witnessed his departure.
Puigdemont's whereabouts were not known, and police made no immediate comment.
The 2017 referendum organised by Puigdemont was declared illegal at the time both by Spain's central government and the Constitutional Court.
Puigdemont has dedicated his career to the goal of carving out a new country in northeast Spain - a struggle that is decades old.
His largely uncompromising approach has brought political conflict with other separatist parties as well as with Spain's central government.
Thursday's event was organised by his political party Together for Catalonia (Junts), hours before a new regional government was to take office nearby.
Police were deployed in a security ring around a section of the park where Catalonia's parliament building is located behind walls.
Puigdemont had earlier announced publicly he was returning to Spain, though he gave no travel details.
Puigdemont's presence in Spain is likely to generate renewed political tension over the smouldering issue of Catalan independence.
The failed secession attempt triggered a protracted constitutional crisis.
It was not immediately clear how authorities would proceed if Puigdemont was arrested.
A contentious amnesty bill, crafted by Spain's Socialist-led coalition government, could potentially clear Puigdemont and hundreds of other supporters of Catalan independence of any wrongdoing in the illegal 2017 ballot.
But the bill, approved by Spain's parliament earlier in 2024, is being challenged by the Supreme Court, which argues the pardon does not apply to embezzlement, unlike other crimes that Puigdemont had previously been charged with.
