Composite materials reinforced with nanometer-sized fillers are widely recognized for enhancing polymer properties and introducing multifunctional capabilities. Nanofiller reinforcement transforms conventional polymers into intelligent materials, offering potential for diverse applications, including electronics, sensors, biomedical devices, aerospace, and defense. This dissertation focuses on the development of soft and rigid nanocomposite materials for multimodal sensors designed for harsh environments and wearable technologies in healthcare and biomedical applications. The research commenced with the fabrication of polymer-derived silicon oxycarbide ceramics (SiOCPDC), reinforced with β-SiC nanopowders (SiCNP) using masked stereolithography (MSLA)-based 3D printing, followed by pyrolysis at 1100 °C. By optimizing SiCNP concentration, a gauge factor (GF) of 6129–8987 was achieved for pressures ranging from 0.5 to 5 MPa, surpassing the sensitivity of existing SiOC ceramics. This cost-effective method makes SiOCPDC a strong candidate for high-performance pressure/load sensing in extreme conditions. Next, a multifunctional hydrogel composed of polyacrylamide (AM) and 2-hydroxyethyl acrylate (HEA), reinforced with zeolite imidazolate frameworks-8 (ZIF-8), was developed. This hydrogel demonstrated excellent mechanical properties, including 808% stretchability, 453.5 kJ/m³ toughness, and minimal hysteresis (2.6%). With a gauge factor of 2.98, it is highly suitable for wearable strain sensing in health monitoring. Finally, a nanocomposite organohydrogel, based on a poly(acrylamide)-co-hydroxyethyl acrylate (PAAm-co-HEA) network reinforced with cobalt imidazole metal-organic framework (Co-MOF), was developed. The organohydrogel exhibited remarkable multifunctional properties, including high stretchability (2225%), toughness, self-adhesion, rapid self-healing, stability over a wide temperature range (-80 to 80 °C), and dual responsiveness for multimodal sensing. It demonstrated capacitive pressure sensitivity (0.75 kPa⁻¹) and thermosensitivity (1.10% °C⁻¹), making it suitable for gait analysis and temperature monitoring. Together, these nanocomposite materials demonstrated significant advancements in high-performance pressure sensing, flexible electronics, and wearable technologies. While the SiCNP reinforced SiOCPDC nanocomposite was utilized for high-performance pressure sensing in extreme conditions, the multifunctional nanocomposite hydrogel and organohydrogel offer robust solutions for wearable sensing systems, providing promising applications in healthcare, biomedical devices, and environmental monitoring.