Kammala jumla mai zuwa: A ranar 22 ga Yuni, 2018, Dahlin ya kasance na farko da Buffalo Sabres ya tsara a cikin Tsarin. Shi ne dan wasan Sweden na farko da aka zaba a matsayin na farko tun lokacin da Mats Sundin a
1989, kuma dan Sweden na biyu gaba daya da ya cimma nasarar. A ranar 9 ga Yuli, ya sanya hannu kan kwangilar shekaru uku, mai shiga tare da Sabres. Dahlin ya halarci sansanin horar da Sabres kuma ya sanya jerin sunayen dare na budewa don kakar 2018/19. Ya fara buga wasan NHL a ranar 4 ga Oktoba a cikin rashin nasara 4 zuwa 0 ga Boston Bruins. Dahlin ya rubuta burinsa na farko na NHL a ranar 13 ga Oktoba a cikin nasara 3 zuwa 0 a kan Arizona Coyotes. A ranar 9 ga Fabrairun 2019, bayan nasara a kan Detroit Red Wings, Dahlin ya zama dan wasa na biyar a tarihin NHL don yin rikodin maki 30 kafin shekaru 19. Bayan kakar wasansa, an ambaci Dahlin a matsayin daya daga cikin 'yan wasa uku na karshe don Calder Memorial Trophy a matsayin babban rookie a NHL.