[7] Her family moved frequently while growing up due to her father's job, living in Hong Kong and the Philippines, before settling in Yokohama, Japan, when Anna was 10.

[7][13] Sawai made her acting debut at age 11 in 2004 in a Tokyo stage production of Annie as the titular character, which was simulcast on Nippon TV.

[13][14] Sawai successfully auditioned for the entertainment conglomerate Avex Inc. in 2006, earning her a management contract and training at their in-house music and dance bootcamp.

[7][10][13] While attending university, Sawai was signed by the Avex Trax record label and in March 2012, she performed the United States national anthem at the Tokyo Dome to begin the 2012 Major League Baseball season.

[20] A month later, Sawai was announced as one of the members of the girl group ARA, an acronym for Avex Rising Angels, and that November they released the music video for their first and only single "Make My Dreams Come True".

[29] In May 2018, she appeared as a dancer in a limited run stage production of The Book, directed by Fuko Takenaka, as part of the Think Tank Bang dance art collective.

[34] That same year, Sawai was cast as martial arts warrior Elle in F9, the ninth film in the Fast & Furious franchise, directed by Justin Lin.

[47][48] In June 2022, Sawai was cast as Cate Randa, the lead role in Legendary's MonsterVerse television series Monarch: Legacy of Monsters.

[50][51] In September 2021, Sawai was cast as the female lead, Lady Mariko, in the FX limited series Shōgun, based on the novel by James Clavell.

[55] RogerEbert.com called her performance "revelatory",[56] and Entertainment Weekly praised Sawai for evolving the role past the 1980 version with "steely strength and spirited temper befitting a more modern audience".

[57] The Hollywood Reporter identified the performance as a career achievement for the actress: "Sawai has been tip-toeing around full-fledged stardom for several years with supporting roles ... but this feels like her arrival.