The poultry industry has long trusted antibiotics for their benefits in chicken production such as improved feed conversion, growth promotion and disease control. However, the emergence of bacterial antimicrobial resistance has resulted in the U.S. federal guidelines prompting the animal industries to voluntarily phase out antibiotic growth promotion in food animals through changes in labelling and soliciting veterinary oversight on their therapeutic use. This situation has resulted in the search for alternatives that would fill the gap antibiotics once occupied. This chapter discusses the role of essential oils and botanicals in improving gut function in poultry, focussing on four major functions of phytobiotics that could potentially contribute to gut health: digestive conditioning, antimicrobial property, immunomodulation and gut microbiota modulation. The chapter discusses the impact of these functions on performance as well as carcass and egg quality. Finally, the chapter looks ahead to future research trends in this area.