The broader application of thermoplastic polyurethane elastomer (TPU) as encapsulation materials is severely restricted by their serious tensile strength and appreciable fire hazard. Hence, 3D hydrangea-like Ti3C2Tx MXene@FeNi layered double hydroxides (M@LDH) are prepared through in situ growth, and incorporated into the TPU. Excitedly, compared to neat TPU, upon adding 3 wt% M@LDH, the obtained M@LDH-3 was capable of achieving a 38.3% and 67.0% decrease in the peak heat release rate (pHRR) and total smoke release (TSR), respectively, exhibiting peerless flame-retardant effects under low addition. In addition, the elongation at break of TPU/M@LDH-3 increased to 637.28% and its tensile strength increased to 42.97 MPa, revealing excellent mechanical properties. The mechanisms for the fire safety and mechanical performance were both studied deeply, expecting this work to illuminate the approach of designing efficient nanomaterials and promote the development of advanced TPU in high-end fields.