For many years, antibiotics were routinely added to chicken feed to prevent diseases and promote growth. However, growing public health concerns, changing consumer preferences, regulatory reforms, and the global sustainability objectives have led to a significant shift toward antibiotic-free poultry production. A 2020 survey demonstrated that approximately 60% of global poultry producers have transitioned to antibiotic-free practices in response to rising consumer demand. At present, antibiotic-free broiler production is not merely a market trend but a crucial move towards a more responsible industry that prioritises public health, meets consumer expectations, and contributes to global efforts to combat antimicrobial resistance (AMR). The WHO attributes up to 700,000 annual deaths to antimicrobial resistance, with the food industry playing a significant role. In response to ban on certain antibiotics, alternative in-feed additives such as pre-probiotics, enzymes, organic acids (OA), and phytogenic have become popular in poultry production. Research has shown that the use of pre- and probiotics can increase feed intake in broilers by 5–10% and reduce disease by 20–25%. Enzymes, on the other hand, have been shown to improve bird performance and feed efficiency, while mitigating environmental impacts, while OA, when added to poultry feed, inhibit Salmonella growth. This review comprehensively examines the mechanisms of action and practical applications of these functional additives, providing valuable insights to support researchers, feed manufacturers, and producers in optimising sustainable, antibiotic-free poultry production systems.