The actresses met at a Beverly Hills coffee shop where Barrymore worked and soon hit it off.
Diaz told Access Hollywood, 'We've known each other so long. We met when she was 14 and I was 16. We met at a place that we both used to hang out in... When I was modelling and she wasn't acting.
'She was working at this coffee shop or this soda shop, and I used to go hang out there and we became friendly.
'Once I started acting, she said, 'Oh, I remember you!' and we used to hang out and we became friends.'
The pair went on to star in Charlie's Angels, which Diaz said is when they became 'like sisters'.