In March 2008 during the 2008 European Aquatics Championships in Eindhoven in her homecountry she swam time-trials for the 2008 Summer Olympics and qualified herself for the 4×100 m and 4×200 m freestyle relay. One month later she took part at 2008 FINA Short Course World Championships in Manchester, United Kingdom where she swam in the heats of the 4×100 m freestyle relay which became world champion later on although she was replaced for the final. She also started in the heats of the 4 × 100 m medley relay and helping the Dutch to achieve the final spot. In this final she was replaced and did not swim, but her team mates finished fourth. Individually she started in the 200 m freestyle and ended up 18th.
De Jonge was selected for the 2008 Summer Olympics in Beijing in where she formed a team with swimmers like Inge Dekker, Chantal Groot, Femke Heemskerk, Linda Bank, Ranomi Kromowidjojo, Manon van Rooijen, Hinkelien Schreuder, Jolijn van Valkengoed and Marleen Veldhuis. She did not qualify for an individual event, but was eligible to swim for the team in the three relay events (4 × 100 m freestyle, 4 × 200 m freestyle, 4 × 100 m medley). She was not chosen to swim in the 4 × 100 m freestyle, but did swim in the series for the 4 × 200 m freestyle, finishing fifth and being eliminated. She saw her team mates win the gold medal at the 4 × 100 m freestyle.