Thousands of fans have flocked to Portugal’s Green List city after the final moved from Istanbul to Turkey.
Earlier in the week, fierce clashes between Chelsea and Manchester City football fans took place ahead of the final.
Images shared on social media show fans singing and fighting in the streets and throwing chairs at each other.
Porto Mayor Rui Moreira said one person was taken to hospital but his injuries were “nothing serious”.
He told Sky Sports News: “As far as I know, and I spoke to the police this morning, it was nothing serious.
“We had to close the bars and pubs because it’s the law, the curfew law, at 10:30 pm people had to leave.
“Between the fans, there was some aggression. A guy went to the hospital, it was nothing serious, no arrests. People have gone to their hotels and it still happens. We also have this experience with our national games.
“You can’t change it, it’s life, but nothing that concerns us so far. “
Chelsea beat Manchester City, who were playing their first Champions League final, thanks to just one goal from Kai Havertz.
The jubilant supporters celebrated the victory until Sunday morning.