Although financial details of the transfer were not released, local media reports suggested Sampdoria paid two million euros for the defender's services.
With Sampdoria currently 13th in Serie A, Bereszynski has set his sights on qualifying for Europe's second-tier competition and hopes to cross paths with his former team mates in the next campaign.
"I think that we have the team to play in the next season in the Europa League," Bereszynski told Sampdoria's TV channel.
"I will keep my fingers crossed for the guys. I believe that Legia Warszawa will beat Ajax and obtain the title. I hope that I'll see them next season in Europe," Bereszynski said on Legia Warsaw's website.
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Sampdoria narrowly missed out on the Europa League two seasons ago, after losing to Serbian side Vojvodina in the third qualifying round of the competition. They travel to third-placed Napoli on Saturday.
(Reporting by Silvia Recchimuzzi in Gdynia; Editing by Clare Fallon)
