Euphoric fans, who at one point in the game had thought Real's record-extending 10th Champions League victory was slipping away, flocked to the Cibeles fountain, a central landmark where the team traditionally mark their successes - less than 1 km (0.62 miles) away from Atletico's usual celebration spot.
"I'm so happy to have beaten Atletico Madrid, to come back after 1-0," said Joaquin, a 27-year-old fan dressed in his club's kit as he headed through the jammed streets to the party.
"Atletico was a good rival ... but it's Real, forever!"
Music blaring from a makeshift stage kept supporters going until around 6am, when the Real team, wearing "La Decima" on their shirts in reference to the 10th title they had coveted for 12 years, finally arrived back with the trophy.
"Even though I waited 6 hours, to see dawn break with Real Madrid and "La Decima" is priceless," one reveller tweeted as the players arrived.
For supporters of Atletico, the 4-1 defeat in the first Champions League final to ever feature two clubs from the same city was especially hard to stomach.
After celebrating the Spanish league title in the streets of the capital only a week ago, the team were denied what would have been their first ever European Cup by their arch-rivals and wealthier neighbours in heart-breaking fashion.
Atletico were on the verge of victory before a goal in the third minute of stoppage time by Real's Sergio Ramos made it 1-1 to take the final into extra time.
"We were massacred, after being so close to winning," said Camino Lopez, a 57-year-old administrator and Atletico fan, after watching the game with friends in a pizza parlour in the traditional Madrid neighbourhood of Lavapies.
Despite the heartache for Atletico fans, who had to endure the night of loud partying, much of the teasing between the two sides remained good-natured.
Fans mingled in bars - and some Real supporters even showed some sympathy for the beaten underdogs.
"It was an excessive beating ... Atletico deserved a better result," said lifelong Real fan and businessman Manuel Burgos, who watched the final in the same pizza restaurant.
Real's official celebrations in the city centre had been supposed to finish around 4.30am, in preparation for a day of voting in the European elections.
Madrid emergency services said 233 people had to be attended to during the festivities and 37 were transferred to hospitals, though all of the injuries or symptoms were minor.