This chapter aims to provide an in-depth examination of engineered nano-biochar (NBC) manufactured from lignocellulosic residues as an innovative option for improving agricultural sustainability and tackling environmental issues. This chapter will explore the methods for transforming accessible and renewable lignocellulosic residues into high-value nano-biochar with improved characteristics. The topic will address the selection of feedstocks, advanced synthesis methods, and the comprehensive evaluation of the resultant nano-biochar, emphasizing its remarkable potential for enhancing soil health, augmenting agricultural yields, and eliminating pollutants from water systems. This chapter will illustrate the diverse advantages of nano-biochar by including new research findings and case examples, therefore advocating for its significance in a circular bioeconomy and sustainable development.