This tutorial review by Roger A. Sheldon and Sander van Pelt provides an overview of enzyme immobilization in biocatalysis, emphasizing its importance in green and sustainable chemical manufacturing. The review discusses the necessity of immobilization to improve enzyme stability, recyclability, and reduce product contamination and allergenicity. Methods of enzyme immobilization are categorized into three types: adsorption on a carrier, encapsulation in a carrier, and cross-linking (carrier-free). Key considerations include immobilization yield, efficiency, activity recovery, enzyme loading, and physical properties of the immobilized enzyme. Recent developments, such as mesoporous silicas, hydrogels, smart polymers, and cross-linked enzyme aggregates (CLEAs), are highlighted. The review also covers the terminology and general considerations in immobilization, including the calculation of immobilization yield, efficiency, and activity recovery. Specific examples of immobilization on prefabricated supports, entrapment, and carrier-free immobilization by cross-linking are discussed, along with the advantages and limitations of each method. The review concludes by emphasizing the ongoing interest in enzyme immobilization and its potential for improving the operational performance of enzymes in industrial applications.This tutorial review by Roger A. Sheldon and Sander van Pelt provides an overview of enzyme immobilization in biocatalysis, emphasizing its importance in green and sustainable chemical manufacturing. The review discusses the necessity of immobilization to improve enzyme stability, recyclability, and reduce product contamination and allergenicity. Methods of enzyme immobilization are categorized into three types: adsorption on a carrier, encapsulation in a carrier, and cross-linking (carrier-free). Key considerations include immobilization yield, efficiency, activity recovery, enzyme loading, and physical properties of the immobilized enzyme. Recent developments, such as mesoporous silicas, hydrogels, smart polymers, and cross-linked enzyme aggregates (CLEAs), are highlighted. The review also covers the terminology and general considerations in immobilization, including the calculation of immobilization yield, efficiency, and activity recovery. Specific examples of immobilization on prefabricated supports, entrapment, and carrier-free immobilization by cross-linking are discussed, along with the advantages and limitations of each method. The review concludes by emphasizing the ongoing interest in enzyme immobilization and its potential for improving the operational performance of enzymes in industrial applications.