2017–2018: Quick-Step Floors Schachmann turned professional in 2017 with . He had to end his season early after a crash on stage 5 of the
Tour de Pologne. In 2018, Schachmann had a break-out season. After an eighth-place finish at the
Flèche Wallonne, he went to his first
Grand Tour, starting the
2018 Giro d'Italia. Here, he won the stage to
Prato Nevoso. He added a bronze medal in the time trial at the
UEC European Road Championships to his record as well as a stage win and third overall at the
Deutschland Tour.
2019–present: Bora–Hansgrohe 2019 , a race that he eventually won For 2019, Schachmann moved to German squad . At the
Tour of the Basque Country, Schachmann won the stage-one time trial to take the overall lead, before securing two more stage wins on stages 3 and 4. He then competed in the
Ardennes classics, placing fifth at both the
Amstel Gold Race and the
Flèche Wallonne and then claimed third place at
Liège–Bastogne–Liège. On 30 June, Schachmann won the
German National Road Race Championships, coming in first in a Bora–Hansgrohe 1–2–3 finish during a demanding race in extreme heat of up to , where only 15 of 190 starters reached the finish line. In July 2019, he was named in the startlist for the
2019 Tour de France. During the stage-13 time trial, he was on his way to post a good time, when he crashed near the end of the course. While he finished the stage, he was later diagnosed with multiple fractures to his hand and had to abandon the Tour.
2020 At the beginning of the 2020 season, Schachmann placed second to
Remco Evenepoel at the
Volta ao Algarve. In March 2020, Schachmann won
Paris–Nice in an edition shortened by one stage due to the
COVID-19 pandemic. He won the first stage and then held on to an eventual lead of 18 seconds over
Tiesj Benoot to become the fifth German winner of the event, and the first since
Tony Martin in
2011. Schachmann continued in good form following the return to racing in August, taking third place at
Strade Bianche. At
Il Lombardia, he suffered an accident when a car entered the race course from the finish. He continued to the finish, where he placed seventh, but fractured his collarbone in the incident. Despite the incident, Schachmann was announced as part of 's
Tour de France octet.
2021 In March, he successfully defended his title at
Paris–Nice, taking the race lead over
Primož Roglič after a crash. He had a strong remainder of the spring season as well, placing third in the
Amstel Gold Race and fourth in the
Tour de Suisse. In June, he won the
German National Road Race Championships. The following month, he placed 10th in the
Road race at the
Summer Olympics. ==Major results==