Stretchable rubber nanocomposites have been investigated for detection in piezoresistive strain sensors. Tensile toughness must be improved while maintaining stretchability to realize high-performance, robust, stretchable nanocomposites. We investigate a stretchable and synergistically toughened silicone nanocomposite-based, piezoresistive strain sensor using multiwalled carbon nanotubes (MWCNTs) and molybdenum disulfide (MoS2). One-dimensional MWCNTs mechanically reinforce the silicone rubber matrix, improving tensile strength by 95% but decreasing fracture strain by 27% at 5 phr, providing an electrical percolation network. Adding two-dimensional nanolayers of MoS2 as a single filler increases fracture strain from 205% (unfilled) to 320% (5 phr MoS2), possibly due to cure retardation in the silicone rubber, preventing over-curing. Silicone nanocomposites exhibit improved tensile toughness at 8.46 kJ/m3 for 5-phr MWCNT-MoS2 hybrids due to the synergistic effects of the hybrid filler, a 125% improvement over unfilled rubber. Nanocomposites maintain a low elastic modulus (<0.45 MPa) suitable for stretchable sensors. The nanocomposite utility is demonstrated as body-attachable, piezoresistive strain sensing with a gauge factor of ∼25.95 (100%<Δε<155%), stretchability of up to 155%, and durability of over 5000 cycles. Toughened nanocomposites with MWCNT and MoS2 hybrid fillers could be useful for applications requiring robust stretchability and sensitivity.