Kühl started playing football as a 5-year-old in Hillerød FC. After nine years in her childhood club, she moved to FC Nordsjælland in 2018. She started on the club's U18 team, but quickly became a regular part of the senior team in Kvindeligaen.

Kathrine is also an integral part of the Danish youth national teams. She made two appearances with the U16 national team, 14 with the U17 national team, and three with the U19 national team, despite being just 17 years old.

When FC Nordsjælland won the cup tournament in July 2020, Kuhl was named Cup Fighter of the Year. An impressive achievement just a month after her 17th birthday.

The strong performances have led to Kühl extending her contract with the club at the end of 2020.