Peterka made his professional debut with EHC Red Bull München of the Deutsche Eishockey Liga (DEL). During the 2019–20 season he appeared in 42 games scoring 7 goals and 4 assists for 11 points.[1] Following the season, Peterka was drafted in the second round of the 2020 NHL draft 34th overall by the Buffalo Sabres[1] Peterka was projected to be a first-round pick before the draft, but fell to the Buffalo Sabres in the second round.[2] He was said to be a great skater with great hands and great ability to make plays at top speed, while drawing a comparison to Patrick Kane.[2] He was also said to be an unrelenting player that never gives up on the puck.[1] Following the draft, Peterka went back to the DEL and played 30 games while scoring 9 goals and 11 assists for 20 points in the 2020-2021 season.[1]
On 12 June 2021, Peterka was signed by the Buffalo Sabres to a three-year, entry-level contract.[3] During the 2021-2022 season, Peterka played for the Rochester Americans, the AHL team for the Buffalo Sabres. He appeared in 70 games during his rookie season, scoring 28 goals and 40 assists for a total of 68 points. He also played in 10 playoff games that year, recording 7 goals and 5 assists for 12 points.[4]
Peterka made his NHL debut with the Sabres on December 29, 2021, in a game against the New Jersey Devils. After the game, the Sabres returned him to the American Hockey League's Rochester Americans.[5]
Peterka's first career NHL goal came in the Sabres' 2022–23 season opener at home against the Ottawa Senators. His goal tied the game at 1–1 en route to a Buffalo 4–1 victory on October 13, 2022.[6]
Joining the senior national team for the first time, Peterka made his World Championship debut at the 2021 edition. Two years later, he rejoined the national team for the 2023 IIHF World Championship, where Germany embarked on an unexpected deep run through the knockout round, defeating the heavily-favoured Team USA in the semi-final to reach the gold medal game.[7] Peterka scored the opening goal of the game, but Germany was ultimately defeated by Team Canada, winning the silver medal, the nation's first at the World Championships since 1953.[8] With six goals and six assists in ten games, Peterka was given the IIHF directorate award for Best Forward, and named to the Media All-Star Team.[9][10]