Catalan separatist Carles Puigdemont addressed more than 100,000 supporters in Perpignan near the Spanish border.
It is the nearest MEP Puigdemont has come to returning to Catalonia since fleeing in 2017.
There were mixed feelings among British MEPs this week as they sat in Strasbourg for the final time before Brexit. But there was delight among Catalan separatists after Carles Puigdemont and Toni Comin were finally allowed to take their seats.
The self-exiled Catalan leader Carles Puigdemont would like to return to Spain for the first time, but it might cost him his freedom.
Announcements and parliamentary procedure will follow Spain's request to lift immunity.
Now fully accredited MEPS, they are here to attend the first plenary of the year. After expressing his joy, Carles Puigdemont told the press the Catalan independence question was a European issue.
A Catalan activist and political commentator has condemned the sentences handed out to pro-separatist as leaders as undemocratic.
Andres da Silva told Euronews' Good Morning Europe that the severity of the sentences was undemocratic and greatly worsened the situation.