Vermeulen made her international senior debut at the 2011 European Short Course Swimming Championships in Szczecin, Poland. At the 2014 short-course world championships in Doha, she won three gold medals for swimming in the heats of all three freestyle relays. Together with her teammates Ranomi Kromowidjojo, Maud van der Meer, and Inge Dekker, she broke the world record in the heats of the 4×50 m freestyle relay.