The striker scored 20 goals in Serie A last season, but was still unable to prevent his club from relegation.
After weeks of negotiations, Simy signed the contract today after undergoing his medical earlier this morning.
The deal is believed to be a loan with obligation to buy for a total of €6m, including bonuses.
Simy has four senior caps for Nigeria.
Salernitana are back in Serie A after an absence of over 20 years.
— US Salernitana 1919 (@OfficialUSS1919) August 19, 2021
— FC Crotone (@FcCrotoneOff) August 19, 2021