Syosset (NY state) ZIP code. ZIP code of Syosset (NY) is 11773. Below you can find map of Syosset, or look up other ZIP codes in New York or other US states. If Syosset's ZIP code is duplicated, and other places have same ZIP code number, you can use our ZIP code searcher by number 11773. Syosset have more then one ZIP code. List of all Syosset's ZIP codes: 11773, 11791.