Benson began her career as a competitive dancer at age three, and transitioned to acting in her teens, first gaining recognition for her role as Abigail Deveraux in the soap opera Days of Our Lives (2004–2007).

Following her film debut in the 2004 comedy 13 Going on 30, she gained international recognition for starring as Hanna Marin in the Freeform drama thriller series Pretty Little Liars (2010–2017).

She has since starred in the films Private Property (2022), Mob Land (2023), and McVeigh (2024), as well as in the Amazon Prime Video psychological thriller miniseries Wilderness (2023).

Aside from acting, Benson has ventured into music, first in 2018 with the soundtrack of Her Smell, followed by her collaboration with G-Eazy in his cover of the Radiohead song "Creep" (2020).

The role required her to both overcome her fear of heights to perform the cheerleading stunts,[3] and to end her contract with Days of our Lives: I got off it, I mean I had talked with the producers about doing this film, and they weren't going to let me do it...

I mean I give all my credit to them, because I have learned so much from being on soap operas and working with amazing actors who've been on there for like thirty, forty years.

[6] Furthermore, she was excited to land a supporting role in Bart Got a Room, which aired mainly on film festivals in 2008 before having a limited release in 2009, because it allowed her to work with William H.

In 2010, Benson starred in the television film Christmas Cupid alongside Christina Milian and Chad Michael Murray, which also aired on ABC Family.

[10] In January 2012, Benson was cast in the film Spring Breakers, after Emma Roberts dropped out due to creative reasons.

[11] The film centers on four college students who are arrested and bailed out by a drug and arms dealer, who sends them out to do some dirty work on spring break.

[13] In the January 21, 2013, episode of the CBS sitcom How I Met Your Mother, Benson appeared as Carly Whittaker, Barney Stinson's half-sister who dated Ted Mosby.

[14] She starred in the 2015 independent horror thriller film Ratter, playing Emma Taylor, a girl who is stalked through her technological devices.

[17] She also appeared in the music videos previously for NLT's "That Girl", One Call's "Black Light", and Hot Chelle Rae's "Honestly".