Scorsone was born in Toronto, Ontario. She is the middle child of five in her family. Her 4 siblings include: 2 older twin sisters and 2 younger siblings: a sister and a brother. One of her older sisters is the actress Francesca Scorsone. (b. 1977)
She attended the Cardinal Carter Academy for the Arts in Toronto where she starred in Oklahoma! and several other productions, as well as alternative school Subway Academy II. In addition, she attended Trinity College in the University of Toronto and in 2005 finished her studies there, earning a degree in postmodern theory.
In 1998, she had a role in one of CBC radio's Mystery Project shows called, "Peggy Delaney". Scorsone played the estranged fifteen-year-old daughter, Amber, who comes from Vancouver to stay with her mom for a school term in Toronto.
The series where Scorsone had her worldwide breakthrough was 1-800-Missing (now simply called Missing). She played the part of Jess Mastriani, a young woman who sees missing persons in visions. After Jess saved some missing persons, she joined the FBI, where a special squad was formed around her, to find missing persons.
In 2010 she joined Private Practice in a recurring role of Amelia, the sister of Derek Shepherd from Grey's Anatomy. She was cast after Eric Stoltz, who was directing one of the show's episodes, heard about the role of Amelia and remembered Scorsone from working with her on My Horrible Year!. He mentioned her to Shonda Rhimes and commented on the resemblance Scorsone had to Patrick Dempsey (the actor who plays Derek Shepherd).
As of July 2010, Scorsone has been promoted to series regular for Private Practice.  She appeared in the third episode of the seventh season of Grey's Anatomy where she and Derek started to reconcile their differences.
In March 2014, TV Line broke the news that Scorsone will be returning to Grey's Anatomy after a 3 year absence. This will be the first type of crossover that has occoured on the show since Private Practice ended in 2012. She will be in season 10 of Grey's and will 'Special Guest Star' from May up until the season ends.
Scorsone is married to Rob Giles of The Rescues since June 2009. On July 6, 2012, she delivered daughter Eliza at her home in Los Angeles, California. Her pregnancy was written into her character's storyline.
In 2012 Caterina was awarded the PRISM award for Best Female Performance in a Drama Series Multi-Episode Storyline, for her portrayal of her Private Practice character's substance abuse.
- 1991–1994: Mr. Dressup
- 1995: Shock Treatment
- 1995: When the Dark Man Calls
- 1996: Ready or Not as Colleen
- 1996: PSI Factor: Chronicles of the Paranormal
- 1996: Flash Forward
- 1996–1999: Goosebumps TV Series
- 1998: Once a Thief
- 1988: Stories of Courage
- 1998: All I Wanna Do
- 1998–2000 Power Play TV Series
- 1999: The Third Miracle
- 1999: The Devil's Arithmetic
- 1999: Teen Knight
- 2000: Common Ground
- 2000: Rated X
- 2001: My Horrible Year!
- 2001: Borderline Normal
- 2002: The Associates TV Series
- 2003–2006: Missing TV Series
- 2008: The Border TV Series
- 2008: The Guard
- 2008–2009: Crash TV Series
- 2009: Alice TV Miniseries
- 2010: Edge of Darkness
- 2010: Castle TV Series
- 2010–2012: Grey's Anatomy Season 7–8 (TV Series)
- 2010–2013: Private Practice Season 3–6 ( TV Series)
- 2014: November Man
- 2014: Grey's Anatomy Season 10 (TV Series)