Early career In her childhood, Wälti played ice hockey as well as football. In 2002, at the age of 8, she started playing for FC Langnau, a boys football team coached by her father. In 2007 she was admitted to the Huttwill Training Centre and, half a year later, she joined Team Bern West. In 2009 she moved to
BSC Young Boys, where she played for a year in the U16 boys' team.
FC Köniz At the same time she played for Team Bern West, Wälti joined
FC Köniz of the
Swiss Challenge League.
BSC YB Frauen In 2009, Wälti joined
BSC YB Frauen, where, in 2011, she won the
Nationalliga A. In the same year, she debuted in the
UEFA Women's Champions League.
Turbine Potsdam In 2013, Wälti signed a contract with
1. FFC Turbine Potsdam of the
Frauen-Bundesliga. She was named captain in her second season and played 110 games between 2013 and 2018.
Arsenal After 110 appearances with the German team, Wälti signed a contract with
Arsenal in July 2018. Wälti was instrumental in Arsenal's 2018–2019 WSL league winning season although only played half of the season after she suffered a
LCL injury which kept her out of football for 9 months In April 2019. She was included in the
2018–2019 PFA Team of the Year. On 13 December 2019, Wälti signed a long-term contract with the club. She later managed to achieve the
2024–25 UEFA Women's Champions League with the club. In September 2025, after 7 years and 183 appearances for Arsenal, Wälti announced her departure from the club.
Juventus On 4 September 2025, Wälti joined
Serie A side
Juventus by signing a contract until 2027. ==International career==