Jonsson debuted in 2005 in Östersund in the relay, coming in 15th. In the following World Cup in Hochfilzen she participated in her first individual, coming in 41st. In early 2006 she participated in the Biathlon World Championships Mixed Relay event in 2006 in Pokljuka, coming in sixth. The 2006-07 Biathlon World Cup began very successfully for her. In the World Cup 3 in Hochfilzen, she came in fourth in the Individual, eighth in the Sprint, and was on the relay team which came in fifth. In the Biathlon World Championships 2007 in Antholz she continued her upward trend and placed fourth in the Sprint. As a high point she led the Swedish team to a gold medal in the mixed-relay. She celebrated her first World Cup victory in the 2006-07 Biathlon World Cup, the mass start in the final round at Khanty-Mansiysk. In the 2008–2009 season she won four more races, including the opening in Östersund where she won the individual race. In the 2009 World Championships in Pyeongchang Jonsson came from 5th place after the opening sprint to win the Pursuit.