The iconic musicians reunited for the first time in years during an encore at McCartney's sold out show at Dodger Stadium.
Fans went wild as the 77-year-old headliner returned to the stage to play Beatles tune Birthday and invited Ringo to join him.
"We've got a surprise for us, a surprise for you, a surprise for everyone," Paul said. "Ladies and gentlemen, the one and only, Ringo Starr."
The two former bandmates embraced and said, "I love you, man," as Starr took his spot behind the drum kit.
The pair also performed "Sgt. Pepper's Lonely Hearts Club Band" and "Helter Skelter".
Ringo, who turned 79 a week ago, threw his drumsticks into the crowd as he ended the short 'reunion' set, and jokingly tried to throw fans McCartney's bass guitar.
The former Beatles drummer wasn't the only surprise guest of the night - McCartney also brought out The Eagles' Joe Walsh for an "Abbey Road" medley to finish the show.
McCartney made it clear he had no plans to retire as he wrapped up the three-hour final night of his North American, telling fans, "Farewell to you guys. Farewell to America. Only one thing left to be said: We'll see you next time!".