INTRODUCTION: Vaccines are one of the great success stories of modern medicine and an increasingly important strategy in the fight against antimicrobial resistance. Glycoconjugate vaccines, consisting of a protein component covalently linked to a glycan antigen, are extremely efficacious in preventing infectious disease. However, glycoconjugates have yet to reach their full potential, with currently licensed glycoconjugate vaccines available against only four pathogens. Protein glycan coupling technology, where glycoconjugates are biologically produced in purpose engineered bacterial cells, has the potential to revolutionize the field by lowering manufacturing cost and increasing flexibility for tailor-made vaccines. AREAS COVERED: This review gives an overview of the past 20 years of PGCT research, discusses the key developments and current status of the technology, and speculates on the future of PGCT-based vaccinology. EXPERT OPINION: PCGT has the potential to overcome some of the limitations of chemical conjugation production methods. The technology has undergone significant development since its inception, and new discoveries are continually driving the field forward. Vaccines currently in clinical trials have demonstrated the potential of the PGCT to deliver effective glycoconjugate vaccines for unmet medical needs.