Development of lightweight and strong structural material using fast-growing poplar wood is promising for green and sustainable engineering. Herein, the overall performances of fast-growing natural poplar wood (NPW) are significantly enhanced via delignification, in situ growth of SiO2 followed by densification. The SiO2/compressed-delignified-wood (SiO2/CDW) nanocomposite obtained exhibits outstanding mechanical properties including a bending strength of 395.6 MPa, a tensile strength of 253.4 MPa, and a toughness of 7.1 MJ/m3, which is improved by 1548 %, 240 % and 590 %, respectively compared with NPW. In addition, the ignition time and burning time of SiO2/CDW nanocomposite are prolonged by 700 % and 112 % compared to those of NPW. Moreover, the specific wear rate of SiO2/CDW is 18 × 10−6 mm3/Nm, which is 72.6 % lower than that of NPW. Moreover, the spring-back ratios of SiO2/CDW in 95 % and in water are 45.2 % and 66.7 %, which are lower than those of CDW (64.6 % and 92.4 %). The SiO2/CDW nanocomposite with enhanced mechanical, flame/water retardant and wear performances are promising to meet the needs of modern engineering as green and sustainable materials.