The purpose is to delay Thursday's vote to install Salvador Illa, from the social democratic PSC–PSOE, as Catalonia's new regional leader, reports Politico.
Illa secured support from the Republican Left of Catalonia, a pro-independence party that was once allied with Puigdemont, last week.
Although Puigdemont's arrest would likely delay the vote on Illa's leadership, enough have said they will support him anyway.
The separatist leader says that returning home is his last option to try to prevent what he claims is a pro-Spanish regional government in Catalonia.
He also asked his supporters to gather and escort him to the Catalan parliament, where he and his supporters hope he will not be arrested. Legal experts think otherwise.
Balloon or disguise?
Mossos D'Esquadra, the regional police in Catalonia, say they intend to comply with the court order to arrest Puigdemont if he returns, writes news agency AP. They have also tried to get the separatist politician to surrender, which was immediately rejected.
The Catalan parliament is located in the large Ciutadella Park, surrounded by Barcelona Zoo on three sides. Access to the park will be restricted and the entire parliament will be searched.
That Puigdemont will try to enter the parliament for the vote has become a topic of conversation in Spain. It has been speculated whether he will come disguised or land on the roof in a hot air balloon, reports Politico.
Did not get amnesty
Carles Puigdemont has been living in exile in Belgium since 2017 after an unauthorized independence attempt from Spain. He is accused of embezzlement in connection with the independence attempt.
Puigdemont did not get amnesty earlier this year when hundreds of Catalan separatists received it after an agreement with the social democratic Prime Minister Pedro Sánchez last autumn.
Puigdemont calls it a "hybrid coup", in a post on X.
He had hoped for amnesty and then try to become Catalonia's regional leader again.