The Finland international has put pen to paper on a three-year deal at Stadio Luigi Ferraris that will come into effect from June 30.
Moisander first joined Ajax in June 2003 but failed to break in to the first team and subsequently had spells at FC Zwolle and AZ, winning the Eredivisie title with the latter in 2009.
The centre-back returned to the Amsterdam Arena in August 2012 and he collected a further two league medals and the KNVB Beker under the stewardship of Frank de Boer.
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