The protection of onboard physical sensors in quadrotor unmanned aerial vehicles (UAVs) from electrostatic discharge (ESD), self-generated radiated emission, and exogenous spatial electromagnetic interference is addressed. A sensor-oriented codesign combining transient voltage suppressor (TVS) clamping with solder-mask opening is proposed, targeting the reliability of the onboard angle sensor and flight-control microcontroller. The ESD failure mechanism at the DC power port is analyzed, and a transient energy-clamping circuit centered on a TVS is designed and verified. Compliance with GB/T 38909-2020 (Guobiao/Tuijian, the Chinese recommended national standard) is confirmed, and the protection is demonstrated by a measured attitude-error reduction from approximately 5 to 1.0° under International Electrotechnical Commission (IEC) 61000-4-2:2025 Level 4 air discharge. Because the 10 V/m immunity required by conventional standards is insufficient near cellular infrastructure, a spatial electromagnetic-immunity investigation under synthesized base-station field exposure up to 61 V/m is designed and an embossed shielding layer of conductive metal is proposed to suppress the RF threat, while the dimpled relief also enlarges the radiating surface to aid heat dissipation. Repeated-endurance reliability under both threats is quantified by the Kaplan–Meier survival framework with protected and shielded configurations showing median survival far beyond the unprotected and unshielded cases. The codesign improves the electromagnetic compatibility of the UAV while adding less than 5 g of mass and is therefore compatible with mass-critical airborne use.