Puigdemont had previously announced his intention to be in Spain on a day that Catalonia's parliament is due to swear in a new president.
The 61-year-old fugitive initially lived in Belgium after bolting Spain in 2017 but his latest place of residence was not known.
Puigdemont kept his travel plans secret before setting out to the wealthy Catalan region in northeastern Spain.
He gave a speech in front of a large crowd of supporters in central Barcelona on Thursday under the noses of police officers, who made no attempt to detain him.
Roadside police units checked vehicles across Barcelona in an effort to nab Carles Puigdemont. (AP PHOTO)
After his speech, in a cloak-and-dagger moment, Puigdemont went into an adjacent marquee tent then hurried out of an exit and jumped into a waiting car that sped away, according to an Associated Press photographer who witnessed his departure.
Authorities, who might have wanted to avoid confrontation with the crowd of several thousand separatist supporters, had set up a police cordon at the nearby regional parliament where Puigdemont was expected to go afterward.
Once Puigdemont had slipped away, roadside police units checked vehicles across the city of 1.6 million people in an effort to nab him.
Puigdemont faces charges of embezzlement for his part in an attempt to break Catalonia away from the rest of Spain in 2017.
As regional president and separatist party leader at the time, he was a key player in an independence referendum that was outlawed by the central government but went ahead anyway.
Those events triggered a political crisis that roiled Spain for months.
Puigdemont's appearance in Barcelona, Catalonia's capital, and his game of cat-and-mouse with police, stole the show on a day when a new government was being sworn in at the regional parliament.
Police were deployed in a security ring around a section of the park where Catalonia's parliament building is located behind walls.
Meanwhile, Puigdemont, wearing a dark suit, white shirt and tie, walked with supporters to the nearby stage where he gave his speech.
"All people have the right to self-determination," Carles Puigdemont told supporters in Barcelona. (AP PHOTO)
Addressing the crowd in the park and at times pumping his fist, 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.
"They have made being Catalan into something suspicious.
"All people have the right to self-determination."
The turn of events was likely to bring political recriminations.
The leader of the Popular Party, the main opposition to Spain's left-of-centre coalition government that has long rebuffed Catalonia's independence movement, condemned Puigdemont's return.
Alberto Nunez Feijoo posted on X that Puigdemont's reappearance was an "unbearable humiliation" that damaged Spain's reputation.
A contentious amnesty bill 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.
