In March 2019, Chadwick was announced as one of the entrants for the inaugural season of the W Series, and followed this by participating in the opening three races of the 2019 F3 Asian Championship. Chadwick was also announced as an official junior driver for Aston Martin Racing, extending an existing unofficial relationship that dated back to 2014. At the first W Series race at Hockenheim, Chadwick put in a dominant performance, leading both practice sessions and qualifying on pole. Despite briefly giving up the race lead to Alice Powell, Chadwick came from behind to take the first win in W Series history. Two weeks later at Zolder, Chadwick again started on pole, however lost the lead to Beitske Visser from the start, and had to fight off Powell after locking up and running wide later in the race, ultimately holding onto second place.
