Leading up to the 2018 NHL entry draft, Dahlin was widely considered the top prospect. He was described as a smart two-way defenceman with a great set of tools, including skating, puck handling, vision, intelligence and shot. Dan Marr of the NHL Central Scouting Bureau described him as an exceptionally talented prospect that would be able to impact his team's fortune in a way similar to Erik Karlsson and Victor Hedman.[5]
On 22 June 2018, Dahlin was drafted first overall by the Buffalo Sabres.[6] He was the first Swedish player to be drafted first overall since Mats Sundin in 1989, and the second Swede overall to accomplish the feat. On 9 July, he signed a three-year, entry-level contract with the Sabres.[7] Dahlin participated at the Sabres' training camp and made the opening night roster for the 2018–19 season.[8] He made his NHL debut on 4 October in a 4–0 loss to the Boston Bruins.[9] Dahlin recorded his first career NHL goal on 13 October in a 3–0 win over the Arizona Coyotes.[10] On 9 February 2019, after a win over the Detroit Red Wings, Dahlin became the fifth defenceman in NHL history to record 30 points before age 19.[11] Following his rookie season, Dahlin was named as one of the three finalists for the Calder Memorial Trophy as the top rookie in the NHL.[12]
On 22 September 2021, Dahlin signed a three-year, $18 million contract with the Sabres. He enjoyed a breakout 2021–22 season, posting new career highs in goals, assists and points and was named to the 2022 NHL All-Star Game.
Dahlin opened the 2022–23 season by setting an NHL record for goals by a defenceman in consecutive opening games, at four, as part of a resurgent Sabres team.[13] Dahlin was later named to his second consecutive All-Star Game, replacing injured teammate Tage Thompson.[14]
On 9 October 2023, Dahlin signed an eight-year, $88 million contract extension with the Sabres.[15]
Dahlin was named captain of the Sabres on 26 September 2024, succeeding Kyle Okposo.[16]
Dahlin also represented the Swedish senior team at the 2018 Winter Olympics, becoming the youngest player to compete in the 2018 tournament, and the youngest to compete in the men's hockey tournament since 1984.[21][22]
^Heather Engel (9 February 2019). "Sabres score three times in second period, defeat Red Wings". NHL.com. Retrieved 11 February 2019. Rookie Rasmus Dahlin had an assist and became the fifth defenseman in NHL history with at least 30 points (six goals, 24 assists) before his 19th birthday (53 games).
