Sini Karjalainen (born 30 January 1999) is a Finnish ice hockey player and member of the Finnish national ice hockey team.

She plays in the Swedish Women's Hockey League (SDHL) with Skellefteå AIK.

[2] She was officially named to the Finnish roster for the 2020 IIHF Women's World Championship on 4 March 2020, before the tournament was cancelled on 7 March 2020 due to public health concerns related to the COVID-19 pandemic.

[3][4] The 2020 World Championship would have been Karjalainen's debut with the Finnish national team at an IIHF-organized international tournament; she appeared on the national roster for various Euro Hockey Tour tournaments, first in 2016.

[5][6][7] She ultimately debuted with the senior national at the 2021 IIHF Women's World Championship as an alternate defenseman on the 25-player roster and skated in five games.