This chapter explores into real-world applications of precision medicine in gastrointestinal illnesses, microbiota-driven cancer therapy and advanced interventions for neurological conditions using extensive case studies. Precision medicine is revolutionising gastrointestinal health by tailoring treatments to individuals’ genetic, environmental and microbiomic characteristics, allowing for therapies that target specific pathophysiological pathways rather than merely managing symptoms. The role of the microbiota in cancer care is becoming more well recognised, with personalised microbiome modulation improving immunotherapy efficacy and lowering adverse effects. Case studies show that microbiota-targeted techniques have the potential to alter therapeutic strategies in gastrointestinal oncology, resulting in safer and more efficient therapies for difficult cancer cases. Precision medicine approaches in neurology, such as gene editing, neurostimulation and artificial intelligence (AI)-guided diagnostics, are showing promise in treating difficult conditions including autism, amyotrophic lateral sclerosis (ALS) and epilepsy. By targeting the underlying causes of disease, tailored medicines that make use of pharmacogenetics, cell-based interventions and integrative technologies enhance patient outcomes. This study emphasises the importance of personalised genetic insights and high-density, responder-guided technologies in maximising treatment strategies. The difficulties of clinical translation are discussed in the study’s conclusion, with particular attention paid to accessibility, cost and ethical concerns. By focussing on these high-impact areas, this study highlights how precision medicine might advance personalised healthcare by providing patients with neurological and gastrointestinal illnesses with better, more individualised therapy options.