After a few minor roles in TV movies, Allen played the role of Marissa Chandler on All My Children from April 21, 2009 to December 21, 2010. For this role, she earned a Daytime Emmy Award award in 2011 in the category Younger Actress in a Drama Series.
Between 2014 and 2016, she played lead roles in the science fiction horror film Extraterrestrial, the psychological thriller Backgammon and the unconventional zombie film It Stains the Sands Red, where she starred a lone woman being chased by a single, relentless zombie throughout the desert. She also acted as executive Producer for the film. This marked the second time she worked with Canadian Director Colin Minihan after Extraterrestrial. In 2015, Allen contributed to the writing of the story for the independent comedy-drama film, Almost Anything.
In 2017, Allen starred in the science fiction drama Incontrol. She also had a co-starring role in the horror film Jigsaw, a sequel to the Saw film franchise.
In 2018, she appeared on the USA Network series Falling Water, replacing Brooke Bloom in the role of Sabine for the series' second season. She has also had a role alongside her Jigsaw co-star Hannah Emily Anderson in the thriller What Keeps You Alive. She is also set to appear in the horror film Descendant as Margaret St. James.
