Abstract: To improve the phase transition temperature range and response rate of poly(N-isopropylacrylamide) (PNIPAm)-based hydrogels and to achieve dynamic tunability of their response behavior, a series of adamantane-modified poly(N-isopropylacrylamide) copolymers (PNIPAm-co-MA-Ad) with varying Ad-MA copolymerization ratio (1.1%–5.06%) were successfully synthesized via free radical copolymerization of N-isopropylacrylamide (NIPAM) with the 2-methyl-2-adamantyl methacrylate (Ad-MA) modified monomer. The molecular structure and actual copolymerization ratios of the resulting polymers were confirmed through Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (¹H NMR), and elemental analysis. Using N,N'-methylenebisacrylamide (MBA) as a chemical crosslinker and NIPAM as the main monomer, a series of PNIPAm-co-MA-Ad-based composite hydrogels (PNIPAm-co-MA-Ad CH) with well-defined three-dimensional network structures, good porosity, thermal stability, and mechanical properties were successfully constructed. To further extend the functional tunability, the small-molecule host β-cyclodextrin (β-CD) was introduced, and the PNIPAm-co-MA-Ad/β-CD CH system was successfully fabricated via host–guest recognition between β-CD and adamantane groups (-Ad). The existence of specific host–guest interactions was confirmed by FT-IR and isothermal titration calorimetry. Finally, it was preliminarily demonstrated that the PNIPAm-co-MA-Ad CH composite hydrogels exhibited favorable temperature- and solvent-induced optically tunable behavior. Moreover, the addition of β-CD altered the hydrophilicity/hydrophobicity balance of PNIPAm-co-MA-Ad within the composite hydrogels, enabling secondary dynamic regulation of the temperature/solvent response characteristics. This work provides a reliable research foundation for further investigation of the solvent- and temperature-responsive mechanisms of PNIPAm-based composite hydrogels and their application in the fabrication of information processing models for encryption, decryption, and recording.