A cyclotriphosphazene compound comprising a fluorinated cyclotriphosphazene compound having at least one fluorine atom substituted with a group represented by Formula 1 below, a method of preparing the cyclotriphosphazene compound, an electrolyte including the cyclotriphosphazene compound, and a lithium secondary battery including the electrolyte are provided: *A-[B—CN]x  [Formula 1] A being a heteroatom having an unshared electron pair; * representing a binding site for bonding the group represented by Formula 1 to a phosphorus (P) atom of the fluorinated cyclotriphosphazene compound; B being a substituted or unsubstituted C1-C5 alkylene group; and x being 1 or 2.