Transistor-type nano-floating gate memory (NFGM) devices have attracted great interest because of their suitability as platforms for integrated circuits and their excellent memory properties with inexpensive fabrication processes make NFGM devices highly promising for the next-generation data storage devices. Herein, electrical memory characteristics of nonvolatile NFGM devices utilizing semiconducting cobalt ferrite (CoFe2O4) nanoparticles (NPs) are reported. 3 kinds of monodisperse CoFe2O4 NPs (5, 8, and 11 nm in diameter), synthesized via a modified thermal decomposition method, are embedded in the NFGM devices. The memory devices based on 8 nm CoFe2O4 NPs have exhibited the best memory characteristics: a large memory window of 73.84 V, fast and reversible switching behaviors, ca. 3×103 of high read current ON/OFF ratio, and outstanding data retention capability with an aid of hydrocarbon chains capping NPs as alternative tunneling dielectric layer. The electrical operations of the NFGM devices on flexible and transparent polymer substrates have also been investigated, which show superb and stable memory performances in repeating program/erase (P/E) cycles and mechanical stability against pure bending.