With no prior acting experience, Diaz auditioned for 'The Mask' at the age of 21. She was cast as the lead female role of Tina Carlyle, opposite Jim Carrey, marking her film debut and an instant success.

After 'The Mask', Diaz took on smaller roles in independent films like 'The Last Supper', 'Feeling Minnesota' and 'She's the One', gaining valuable acting experience and developing her craft beyond her initial success.

Her role as Kimberly Wallace in the romantic comedy 'My Best Friend's Wedding', alongside Julia Roberts and Dermot Mulroney, solidified her status as a leading actress and broadened her audience appeal.

Diaz showcased her comedic talent in the Farrelly brothers' hit comedy 'There's Something About Mary'. The film was a massive box office success, and she received critical acclaim for her performance. Also, she starred in 'Very Bad Things' and provided voice acting for 'Antz'.

Diaz demonstrated her versatility by taking on more challenging and unconventional roles. She starred in 'Being John Malkovich', which garnered widespread critical praise. That same year she also played Christina Pagniacci in 'Any Given Sunday'.