Years after appearing in Miss Potter, Boynton headed to the big screen again. She appeared in Osgood Perkins 2015 horror film The Blackcoat's Daughter opposite Emma Roberts and Kiernan Shipka. She reunited with Perkins again in 2016, for the spooky haunted house feature I Am The Pretty Thing That Lives In The House. That was the same year that Boynton appeared in the music drama Sing Street, which some compared to a grittier, Irish version of High School Musical.