De Jonge made her international debut in
Helsinki at the
European Short Course Swimming Championships 2006. She won a silver medal in the 4×50 m freestyle relay alongside
Inge Dekker,
Chantal Groot and
Marleen Veldhuis. Individually, she ended up 22nd in the 50 m freestyle and 18th in the 100 m freestyle. At the
European Short Course Swimming Championships 2007 in
Debrecen, she only swam in the heats of both relays.
2008 In March 2008, representing her country at the
2008 European Aquatics Championships in
Eindhoven, she swam time-trials for the
2008 Summer Olympics. De Jonge qualified for the 4 × 100 m and 4 × 200 m freestyle relay. One month later she took part in the
2008 FINA Short Course World Championships in
Manchester,
United Kingdom, where she swam in the heats of the 4×100 m freestyle relay in which she became world champion, although later on she was replaced for the final. She also started in the heats of the 4 × 100 m medley relay and helped the Dutch to achieve the final spot. In this final she was replaced and did not swim, but her teammates finished fourth. Individually she started in the 200 m freestyle and ended up 18th.
2008 Summer Olympics De Jonge was selected for the 2008 Summer Olympics in
Beijing in which she formed a team with swimmers 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 teammates win the gold medal at the 4 × 100 m freestyle. ==Personal bests==