McCartney warned members of the crowd to never hold back their feelings, as he did with Lennon after the group broke up.
"That's it," McCartney said after finishing the song on a baby grand piano. "If you wait to tell someone you love them, it's too late."
The set only seemed to pick up speed as the night edged toward midnight. With the crowd yet to diminish, he played "Live and Let Die" accented by onstage pyrotechnics and fireworks.
The entire crowd joined in on "Hey, Jude" before McCartney and his four-piece band left the stage. He returned waving a Tennessee state flag and played a three-song encore that included "Day Tripper" and "Get Back."
He returned for a second encore that included a rollicking version of "Helter Skelter." A member of the crowd tossed McCartney a stuffed toy walrus, alluding to a cryptic nickname given to him by Lennon, and McCartney concluded his first show at Bonnaroo by singing "Carry That Weight" to the toy he placed atop his piano.
Follow AP Music Writer Chris Talbott: http://twitter.com/Chris_Talbott.