2010s: Worldwide recognition
Tonkin has appeared on the Australian television shows Packed to the Rafters and Home and Away. In September 2010, she made her film debut starring in the Australian action ensemble film Tomorrow, When the War Began. The film revolves around a group of teenagers waging a guerrilla war against an invading foreign power in their fictional hometown of Wirrawee. Tonkin played the rich and uptight Fiona Maxwell. In December 2010, a sequel was announced, in which Tonkin was expected to return, but production never eventuated.
In January 2011, Tonkin moved to Los Angeles to pursue her international acting career. In March 2011, she was cast as Faye Chamberlain in The CW's supernatural drama series The Secret Circle, which premiered on 15 September 2011 to over 3.5 million viewers. The series follows a group of young witches who form a secret coven. Tonkin received critical acclaim for her performance, with critics calling her the break-out star of the series; she was featured on Variety's list of "new faces to watch", and named one of 2011's break-out TV stars by E! Online. The show, however, had only one full season and was cancelled on 11 May 2012.
In August 2010, Tonkin was cast in the 3D horror film Bait 3D. Filming took place in the coastal city of Gold Coast, Queensland; the film follows a group of strangers trapped in a supermarket with a pack of great white sharks after a freak tsunami. Tonkin reunited with her H2O: Just Add Water co-star Cariba Heine for this film, which was expected to be released in Australia in September 2012. In August 2012, Tonkin joined the cast of The CW television series The Vampire Diaries, in the recurring role of Hayley, a friend of Tyler's. Once again, she reunited with a co-star from H2O: Just Add Water—this time Claire Holt, who portrays Rebekah Mikaelson on the show.
On 11 January 2013, The CW confirmed that a spin-off series to The Vampire Diaries was in the works, titled The Originals. The series revolves around the Original Vampire family members, and Tonkin would be "heavily featured in the prospective pilot" of the series. The CW confirmed on 13 February that Claire Holt would also join the cast of The Originals, marking the third time Tonkin and Holt have starred together on a show.
On 15 May 2017, SBS announced that Tonkin had been cast in their new four-part drama Safe Harbour about a group of Australians on a sailing vacation who come across a boat of refugees. Tonkin revealed on Instagram that her character's name would be "Olivia". The series received critical acclaim and won an International Emmy Award for Best TV Movie or Miniseries in 2019. She next appeared on an episode of The Affair as Delphine, a promiscuous art protégée.
After her having expressed in interviews a desire to continue working in Australia, it was announced on 20 August 2018 that Tonkin had been cast in Bloom, to be aired on the streaming platform Stan, as the young Gwen Reid, a character whose older version is portrayed by Jacki Weaver. In 2019, Tonkin wrote and directed her first short film, Furlough, which was screened around the world in film festivals in 2020. Since 2019, she has participated in the Tribeca Chanel Women's Filmmaker Program, aimed at empowering female directors.
