In 2019, Horder won the German Match Play Championship and finished third at the English Girls' Open Amateur Stroke Play Championship. She also represented Germany at the
World Junior Girls Championship in Canada. In 2020, Horder joined the German National Team and won the
European Girls' Team Championship in
Hrubá Borša, Slovakia together with
Charlotte Back,
Sophie Witt and
Paula Schulz-Hanssen. In the final against Sweden, Horder won her match 4 and 3 paired with Charlotte Back for a final scoreline of 2.5 to 0.5 in Germany's favor. Her team captured the bronze at the
2023 European Ladies' Team Championship. Horder attended
Texas Tech University and played with the
Texas Tech Red Raiders women's golf team between 2021 and 2023. In 2023, she transferred to
Mississippi State University where she helped the
Mississippi State Bulldogs women's golf team win their first-ever
Southeastern Conference title in 2024. In June 2023, Horder won
The Women's Amateur Championship at
Prince's Golf Club in England. She defeated world number one
Ingrid Lindblad in the semifinals and
Annabelle Pancake of the United States 7 and 6 in the final to become Germany's third champion in six years, joining
Leonie Harm (2018) and
Aline Krauter (2020). ==Amateur wins==