This chapter provides an in-depth examination of chimeric enzymes, emphasizing their design, engineering, and potential to transform catalytic processes in the pulp and paper industry. It begins by outlining the fundamental principles behind chimeric enzyme construction, wherein functional domains from different parental enzymes are fused to create multifunctional biocatalysts with enhanced stability, activity, and substrate specificity. Various design strategies—including domain fusion, linker optimization, modular rearrangement, and rational or semi-rational engineering—are discussed to demonstrate how tailored architectures improve catalytic performance under industrial conditions. The chapter also highlights advanced enzyme-engineering approaches such as directed evolution, site-specific mutagenesis, and computational modeling, which further refine chimeric constructs. Practical benefits, including improved thermostability, reduced chemical dependence, and enhanced delignification, are explored alongside emerging applications in biobleaching, deinking, refining, and pitch control. Forward-looking perspectives emphasize the role of chimeric enzymes in enabling greener, more efficient, and sustainable paper production within a circular bioeconomy framework.