Breeds attended Sutherland Shire Christian School from kindergarten to year 10 and then St Andrew's Cathedral School for Years 11 and 12. She was also a Drama Captain in 2005. At the end of 2005, Breeds, in her capacity as Drama Captain, along with the Music Captain organised a Year 12 Revue; she participated in a few acts including a Spice Girls tribute and a mashup song, co-written with Nick Hansen, titled Steal My Essays/Textual Healing which discusses the Year 12 NSW HSC Advanced English Syllabus she completed in 2005.
Her acting career started with appearences on several TV commercials, followed by a guest role in 2000th episode of Water Rats called "Jump in the Mouth". She landed her first lead role as Leah Pointin in the 2008 Australian film Newcastle.
Breeds played Cassie Cometti in series the third series of Blue Water High, but appeared in the third episode of second series aswell. It was during filming on Blue Water High that she successfully auditioned for the role of Ruby Buckton on Home and Away, and her first scenes aired in June 2008. In June 2012, TV Week's Erin Miller reported that Breeds had filmed her final scenes and had left Home and Away after four years. The actress made her last appearance as Ruby during the episode broadcast on 15 August 2012.
In August 2012, Nellie Andreeva from Deadline.com announced that Breeds had been cast in Rob Greenberg's We Are Men as Abby Russo. We Are Men marked her first US television role, however, the show was cancelled due to poor ratings. Breeds also appears in the 2013 Hindi-language Bollywood film Bhaag Milkha Bhaag.
In 2015, Breeds appeared in the sixth season of Pretty Little Liars and was cast as Aurora in the supernatural series The Originals. Her other recent roles include her portrayal of Moly Meldrum's fiancée Camille in the 2016 miniseries Molly. On 19 February 2016, it was announced that Breeds will star in Miranda's Rights, a legal soap about a group of lawyers who work and live together. After a competitive audition process, Breeds got the lead role.
In 2009, Rebecca met and began dating her Home and Away co-star Luke Mitchell. The couple announced their engagement in May 2012 and got married in January 2013.
|2008||Newcastle||Leah Pointin||Feature film|
|2013||Bhaag Milkha Bhaag||Stella||Bollywood film|
|2000||Water Rats||Episode: "Jump in the Mouth"|
|2006–08||Blue Water High||Tina/ Cassie Cometti||Season 2 episode 3/ season 3 Series regular|
|2008–12||Home and Away||Ruby Buckton||Series regular|
|2013||We Are Men||Abby Russo||Series regular|
|2015-2016||Pretty Little Liars||Nicole Gordon||Episodes: "No Stone Unturned", "FrAmed" and "Did You Miss Me?"|
|2015||The Originals||Aurora de Martel||Recurring role|
- She is married to Agents of S.H.I.E.L.D. star Luke Mitchell who plays Lincoln Campbell, since January 2013.
- She was in Blue Water High with Eka Darville who portrays Diego in the first season of The Originals.
- She portrayed Camille O'Connell under the disguise of Aurora in A Ghost Along the Mississippi.