The 25-year-old, who can play at right and left-back, arrives at Elland Road having signed a two-year deal with the club.
The defender started his career with Italian side Brescia, where he made more than 100 appearances.
During his time with the Italian side he won promotion when Brescia won the 2010 Serie B Play-Offs.
In January 2012 he moved to Sampdoria and Berardi once again helped his club secure promotion to Serie B through a successful Play-Offs campaign.
The defender also has international caps to his name after playing for the Switzerland Under-20s, Under-21s and he made his full senior international debut in August 2011.
The defender is United’s fifth signing of the summer following the arrival of goalkeeping duo Marco Silvestri and Stuart Taylor, midfielder Tommaso Bianchi and striker Souleymane Doukara.
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