Police have arrested 15 people during a massive security operation organised for the FA Cup final.
Most fans were well-behaved and caused no trouble
Officers said they were pleased with the low number of arrests, which were made as up to 100,000 people visited the city to see Manchester United take on Millwall.
Most arrests were for suspected ticket touting, though six were for minor public order offences, and one was made when a fan ran onto the pitch.
South Wales Police said a lot of officers remained into the evening as many fans stayed on after the game.
There had been some concerns about trouble between rival fans.
But Chief Superintendent Jeff Cooksley said: "There were a few minor flash points throughout the day that had the potential to create disorder, but the professionalism of the officers combined with a tried-and-tested policing plan ensured that no violence occurred."
He commended the behaviour of both sets of fans.
Extra-tight safety measures had been put in place - not only because of concerns of clashes between opposing fans, but also because of fears of a terrorist attack.
Fans young and old travelled miles or the match
Police said there was no specific threat, but armed officers posted at key spots on the outskirts of the city had been carrying out random checks on incoming lorries since midweek.
Assistant Chief Constable Stephen Cahill said : "There was no specific intelligence on this event, but there is a worldwide risk.
"We are not linking it directly to events at Manchester United. Sadly, because of what happened in Madrid, events worldwide and what happened at Manchester United, we have to take the risk at major events seriously."
Around 1,000 officers were working in and around the stadium. Many were brought in from other parts of south Wales, and from London and Manchester.
Inside the ground, an additional 180 stewards - from the home grounds of Manchester and Millwall - were helping with crowd control, and bags were searched and x-rayed for illegal objects.
Hotels and guest houses have been booked up for weeks, and businesses in the city were extremely busy, with pubs drafting in additional staff and ordering extra supplies.
Some shops and restaurants, however, clearly thought the fans might be more than they could cope with, as some were displaying "Closed for the FA Cup" signs.
The FA Cup final has come to Cardiff four times
The rise in visitor numbers has not just had a knock-on effects for the economy of the Welsh capital city.
Accommodation as far afield as Swansea, 40 miles away, has been booked out for the match weekend.
The Millennium Stadium was filled to its 72,500 capacity, with an extra 30,000 fans packing the pubs in the city to watch the game on TV.
Inside the stadium, 90 volunteers from St John Ambulance in Wales provided First Aid support.
This is the fourth year Cardiff has hosted the event, because the final's former home, Wembley stadium, is being re-developed.