Cellulose-based aerogels are a research hotspot as third-generation high-performance structural materials, prized for their ultra-lightweight nature, tunable mechanics, and eco-friendliness. This chapter systematically surveys recent advances in fabricating ultra-lightweight, high-strength CBAs through preparation strategies and structural design. Key techniques analyzed include: physical crosslinking (e.g., directional freezing), chemical cross-linking (e.g., esterification), and composite reinforcement (e.g., nanofillers based interfacial regulation), revealing microstructure-mechanical property relationships. It highlights structural designs (e.g., multiscale structure) and new technology for enhancing mechanics. Applications in energy-efficient buildings, aerospace, and electronics are detailed, emphasizing lightweight advantages. Finally, the review addresses scalability challenges, environmental stability limits, multifunctional synergy needs, and modeling gaps, proposing future directions involving microfluidics, machine learning, and renewable solvents to guide structural materials innovation.