The 31-year-old, who has made six appearances for the Azzurri and moved from Palermo to Torino earlier this month, has also been fined 20,000 euros (£13,000), bt the Italian Football Federation.
Di Michele had been accused of betting "directly or through third parties, on the results of official matches organised by the FIGC". The maximum possible ban was three years.
Top-flight team Udinese were fined 15,000 euros with Serie B sides Vicenza and Mantova having to pay 7,000 euros following the probe. Three lesser known players also received bans of between three months and five months plus 20 days.
Italian players were prohibited from betting on any football match worldwide in 2005, before last year's match-fixing scandal broke.