Lawston's acting debut was in the 2005 film Flightplan, where she played Julia, the six-year-old daughter of Kyle Pratt (Jodie Foster) who was kidnapped onboard a plane. In 2006, she played Julie Grant in the Law & Order episode "Thinking Makes It So". She was featured in the 2007 film Dan in Real Life where she played Steve Carell's daughter Lilly Burns. In 2010, she played Nicky in an episode of Blue Bloods.