Native layered and two-dimensional materials such as transition metal dichalcogenides (TMDCs) and layered double hydroxides (LDHs) possess highly attractive intrinsic properties. Both the enhancement of these intrinsic properties and the addition of new properties through functionalization are relevant to a range of catalysis, optoelectronics, and electrochemical energy conversion applications. Effective functionalization techniques allow for the modulation and control of physical and chemical properties such as chemical reactivity, chemical stability, and ionic conductivity. Thus, the production and characterization of functional materials with properties tailored for specific applications are highly desirable. In this work, the functionalization of layered double hydroxides, transition metal dichalcogenides, and high-entropy perovskite oxides are achieved through both existing and new methodologies including ion exchange of anionic species, covalent surface functionalization with organometallic and organic species and non-covalent functionalization via metallic nanoparticle exsolution. The success and impacts of these functionalization processes on the parent materials' structural, chemical, and electronic properties are investigated using bulk and surface-sensitive material characterization techniques. First, the basal plane of NbS2 nanosheets are covalently functionalized by a coordinatively unsaturated organometallic fragment generated from in situ photolysis. This strategy may be valuable for optoelectronic, sensing, and energy storage applications. Second, the intrinsic OH- conductivity of MgAl LDHs is shown to be greatly influenced by the intercalated anion and is related to the framework of the Hofmeister series. Tuning the strength and flexibility of the hydrogen-bonded water network is vital to the underlying OH- conduction mechanism in LDHs. Investigations with selective covalent surface modifications of the LDHs further reveal that the exterior basal surfaces, rather than the interlayer spaces, are the primary route of OH- conduction in bulk LDHs. These LDHs show promise as hydroxide conduction anion exchange materials in electrochemical energy conversion applications. Finally, high-entropy perovskite oxides are used as compositionally tunable supports for the exsolution of alloy nanoparticles. The composition and reducing conditions of the high-entropy support play a crucial role in the composition of the resulting nanoparticles.