McClements is best known for her starring role as Rachel Goldstein on the Australian police drama Water Rats from 1996 to 1999. McClements had a recurring guest role on The Secret Life of Us in 2001, for which she won the AFI Award for Best Actress in a Guest Role in a Television Drama. She later starred as Rosie in the 2003 drama series CrashBurn and appeared in the Network Ten telemovie Mary Bryant in 2005. In 1993 she had a role in The Girl from Tomorrow Part II: Tomorrow's End.

Her latest television roles include Inspector Kerry Vincent, in the Australian police drama, Rush, and psychologist Christine Williams in the Showcase drama, Tangle. A second and third season of Tangle and Rush respectively have both been announced.[1][2]

Catherine is also an accomplished stage actress, who has appeared in stage productions for many theatre companies, including Sydney's Belvoir St Theatre, the Melbourne Theatre Company and The Playhouse, also in Melbourne. In the late 1980s, Catherine worked in Adelaide with the South Australia Theatre Company.

She successfully auditioned for the prestigious National Institute of Dramatic Art when she was 17. She graduated from NIDA in 1985, alongside Baz Luhrmann and Sonia Todd.[3][4][5]

Her partner is actor Jacek Koman who also guest starred in The Secret Life of Us as Dominic.[6] They have a daughter named Coco (born July 2001) and a son named Quincy (born May 2007). Her sister is Georgina McClements, a producer, who has credits in shows such as Summer Heights High and Real Stories.