Fem van Empel was born on September 3, 2002, in 's-Hertogenbosch, the Netherlands. She grew up in Sint-Michielsgestel, where she started playing soccer at the age of six. Later, she added cycling as a second sport, a combination she managed to maintain for quite some time. In 2018, she even moved to the higher-level club RKSV Nuenen, but eventually, in 2019, she quit soccer to focus entirely on cycling.
In 2020, she immediately finished fifth at the Junior World Championships, and later that year, she joined Pauwels Sauzen-Bingoal. For that team, she had an impressive cyclo-cross season in 2020/2021, with the world title in the U23 category in Ostend in Belgium as the absolute highlight. She confirmed her status as a top talent the following winter with World Cup victories in Val di Sole and Flamanville.
In the 2022/2023 cyclo-cross season, Van Empel continued on her established path, which had also caught the attention of (at the time) Jumbo-Visma. In September 2022, the team announced that Van Empel would join the Dutch team starting January 1, 2023. After World Cup wins in Waterloo, Fayetteville and Maasmechelen, she also won her first major championship title among the pros at the European Championships in Namur in late 2022. Later, she added victories in Antwerp and Dublin before changing teams.
In her first month with what was at the time Jumbo-Visma, Van Empel focused mainly on the Cyclo-cross World Championships in Hoogerheide, where she clinched victory after a battle with rival Puck Pieterse. She then turned her attention to some mountain biking races and her first major stage race, the Giro Donne, where she finished eleventh. She also placed sixth in the Tour de l'Avenir Féminin and third at the European Gravel Championships.