In 2015, it was announced that Hartley had been cast in a series regular role on the NBC drama series "This Is Us", which debuted in September 2016. He and the cast won Outstanding Performance by an Ensemble in a Drama Series at the 24th Screen Actors Guild Awards. In 2017, he had a co-starring role in the comedy film "A Bad Moms Christmas". In August 2020 Hartley signed on to star and executive produce a film adaptation of "The Noel Diary", based on the novel of the same name.