McCartney performed at Apple Park in Cupertino Tuesday night.
Before the event, SKY7 video showed a line of employees waiting to get in.
He performed Beatles classics like "Hey Jude," "Help!" "Love Me Do," and "Ob-La-Di, Ob-La-Da."
CEO Tim Cook sent out a message after the celebration was over Tuesday night.
He posted a video on social media with the caption:
"50 years of Apple, 50 years of innovation. Thank you to our teams, our users, and everyone who's been part of the journey."