In 2009, she moved to Eindhoven to train with Jeanet Mulder, after she had qualified for the 2010 European Aquatics Championships she changed coach to Jacco Verhaeren.

Van Rouwendaal (swimming the backstroke lead-off leg) and her teammates Moniek Nijhuis (breaststroke), Inge Dekker (butterfly), and Ranomi Kromowidjojo (freestyle) broke the Dutch record in this event.

[8] At the 2014 European Aquatics Championships in Berlin, Van Rouwendaal won the gold medal in the 10 km open water, upsetting reigning Olympic champion Éva Risztov of Hungary by 1.1 seconds.

With her teammates Marcel Schouten and Ferry Weertman she won another gold medal in the 5 km team time trial.

The team (also consisting of Inge Dekker, Femke Heemskerk, and Ranomi Kromowidjojo) broke China's four year old world record by more than 3 seconds with Van Rouwendaal splitting 1:52.73.

In the 5 km team time trial she and her teammates Marcel Schouten and Ferry Weertman finished in tied second place.

In the pool, Van Rouwendaal won the silver medal in the 400 meter freestyle behind defending champion and world record holder Katie Ledecky, who had dominated this event since 2013.

At the 10 km event at the European Open Water Championships in Hoorn, the Netherlands, Van Rouwendaal missed a turn near the finish while in leading position.

[13] At the 2016 Summer Olympics in Rio de Janeiro, Van Rouwendaal missed the final of the 400 m freestyle, finishing 19th in the heats.