Simeoni-Wagner began her journalistic career at the Stuttgarter Zeitung before joining the sports desk of the Frankfurter Allgemeine Zeitung (FAZ) in 1981, where she worked for 40 years until her retirement. In addition to equestrian sports, she covered rowing, weightlifting, and multiple Olympic Games, building a reputation for her analytical approach and critical perspective on international sports governing bodies such as the IOC.

Her work earned her numerous accolades throughout her career, including the prestigious Theodor Wolff Prize (1981) and the "Silbernes Pferd" media award (2004). She was named German Sports Journalist of the Year in both 1996 and 2012. In 2022, the German Equestrian Federation (FN) honored her contributions to the sport with the Silver Equestrian Cross.

Beyond her daily journalistic work, Simeoni-Wagner authored several books. In the equestrian world, she was particularly well known for her co-authorship of two books with dressage icon Isabell Werth: Four Hooves Carry My Soul and What Kind of Person Is My Horse?.