The winking winger, 24, kissed and cuddled the 28-year-old socialite in a Hollywood club before they headed to her sister's home.
Ronaldo's move from Manchester United to Real Madrid sets a new world record.
A clubber who witnessed their frolicking said: "They were sucking each other's faces off like their plane was going down.
"At one point Ronaldo had a bottle between his legs and Paris was stroking it. It was very racy."
After sharing steamy cuddles and expensive champagne for two hours, Paris headed to sister Nicky's home in the Hollywood Hills at 2.05 a.m.
Ronaldo, 24, joined her there an hour later after a brief stopover at his hotel.
He left at 5 a.m. with a broad grin plastered across his face.