Mezue ahịrịokwu na-esonụ: Na 13 Septemba 2018, a gbanwere Karlsson (ya na Francis Perron) na San Jose Sharks na mgbanwe maka Chris Tierney, Dylan DeMelo, Josh Norris, Rūdolfs Balcers, nhọrọ mbụ nke Sharks na 2020, nhọrọ nke abụọ na
2019 na nhọrọ nke abụọ na 2021. O nyere goolu mbụ ya na Sharks na 18 Nọvemba na mmeri 4-0 na St. Louis Blues. Mgbe ọ na-amalite nwayọ na oge, Karlsson ghọrọ onye agbachitere nke ise na akụkọ ntolite nke nwere opekata mpe otu enyere aka na egwuregwu iri na anọ na-esochi mgbe mmeri 7 <unk> 2 meriri Edmonton Oilers na 8 Jenụwarị 2019. Na Disemba 23, a kwụsịtụrụ Karlsson maka oge mbụ na ọrụ ya maka egwuregwu abụọ maka ịlele iwu na-akwadoghị na isi onye ọkpụkpọ Los Angeles Kings Austin Wagner. Mmerụ ahụ groin mere ka Karlsson ghara ọtụtụ egwuregwu na nso ngwụcha oge tupu ọ laghachi maka egwuregwu ikpeazụ nke oge megide Colorado Avalanche. Ọ ga-ejedebe oge ahụ na isi ihe 45 na egwuregwu 53, akara ya kachasị dị ala kemgbe oge 2012-13. Karlsson nyeere San Jose aka iru na Western Conference Finals n'oge 2019 playoffs, ọ bụ ezie na ọ merụrụ ahụ ọzọ na egwuregwu megide St. Louis Blues, na-eme ka ọ na-efu egwuregwu ikpeazụ nke San Jose nke playoffs mgbe ndị otu ahụ furu efu 5<unk>1 na Egwuregwu 6. Ọ ga-ejedebe egwuregwu playoff na isi iri na isii n'egwuregwu iri na itoolu. N'abalị iri atọ na otu nke ọnwa Mee, a wara ya ahụ n'akpịrị.