In July 2018, it was announced that Fennell was hired by her close friend Phoebe Waller-Bridge as head writer for the second season of the BBC America series Killing Eve, replacing Waller-Bridge, who remains as a producer. Fennell also become one of the show's executive producers. Speaking to The New York Times, Fennell said "Phoebe [Waller-Bridge] and I had worked together in the past, and we’ve been friends for nearly 10 years. We met on a film — Albert Nobbs — which we both had tiny parts in. I started in the very early days as a writer in the Season 2 writer's room. Because it's such an unusual show, they did a very loose writers' room for a week just to see, and then wonderfully and luckily for me they promoted me to head writer. " The second season began broadcast in April 2019. At the 71st Primetime Emmy Awards, Fennell was nominated for a Primetime Emmy Award for Outstanding Writing for a Drama Series for the season 2 episode "Nice and Neat".