This systematic review aims to evaluate the therapeutic potential of L-carnitine (LC) in treating various psychiatric and neurological disorders. LC, a vital nutritional supplement, has been extensively studied for its cardioprotective effects and its potential benefits in neurological and psychiatric conditions. The review conducted a comprehensive search in multiple databases up to November 2023, resulting in 1479 articles, from which 962 were retained after duplicate removal. A meticulous re-screening identified 60 relevant articles focusing on conditions such as hepatic encephalopathy (HE), neurodegenerative diseases (NDs), peripheral nervous system diseases (PNSDs), stroke, Raynaud’s syndrome (RS), and cognitive disorders (CD). The review found that LC has demonstrated favorable therapeutic effects in managing HE, Alzheimer’s disease (AD), carpal tunnel syndrome (CTS), CD, migraine, neurofibromatosis (NF), PNSDs, RS, and stroke. However, its efficacy is relatively limited in conditions like amyotrophic lateral sclerosis (ALS), ataxia, attention deficit hyperactivity disorder (ADHD), chronic fatigue syndrome (CFS), Down syndrome (DS), and sciatica. The review also discussed the adverse effects (AEs) reported in controlled clinical trials, which were generally mild and gastrointestinal-related, with only a few patients discontinuing treatment due to serious AEs. The potential mechanisms of action of LC include its role in reducing oxidative stress (OS), modulating inflammatory mediators (IMs), improving mitochondrial function (MD), enhancing fatty acid transport function, and supporting cholinergic neurotransmission. LC acts as an antioxidant and anti-inflammatory agent, protecting tissues from ROS damage and reducing OS markers and pro-inflammatory cytokines. It also regulates cell apoptotic signaling and enhances antioxidant activity. In conclusion, LC shows promise in treating several psychiatric and neurological disorders, but its efficacy varies across different conditions. Further research is needed to confirm its benefits and to explore its mechanisms of action in more detail.This systematic review aims to evaluate the therapeutic potential of L-carnitine (LC) in treating various psychiatric and neurological disorders. LC, a vital nutritional supplement, has been extensively studied for its cardioprotective effects and its potential benefits in neurological and psychiatric conditions. The review conducted a comprehensive search in multiple databases up to November 2023, resulting in 1479 articles, from which 962 were retained after duplicate removal. A meticulous re-screening identified 60 relevant articles focusing on conditions such as hepatic encephalopathy (HE), neurodegenerative diseases (NDs), peripheral nervous system diseases (PNSDs), stroke, Raynaud’s syndrome (RS), and cognitive disorders (CD). The review found that LC has demonstrated favorable therapeutic effects in managing HE, Alzheimer’s disease (AD), carpal tunnel syndrome (CTS), CD, migraine, neurofibromatosis (NF), PNSDs, RS, and stroke. However, its efficacy is relatively limited in conditions like amyotrophic lateral sclerosis (ALS), ataxia, attention deficit hyperactivity disorder (ADHD), chronic fatigue syndrome (CFS), Down syndrome (DS), and sciatica. The review also discussed the adverse effects (AEs) reported in controlled clinical trials, which were generally mild and gastrointestinal-related, with only a few patients discontinuing treatment due to serious AEs. The potential mechanisms of action of LC include its role in reducing oxidative stress (OS), modulating inflammatory mediators (IMs), improving mitochondrial function (MD), enhancing fatty acid transport function, and supporting cholinergic neurotransmission. LC acts as an antioxidant and anti-inflammatory agent, protecting tissues from ROS damage and reducing OS markers and pro-inflammatory cytokines. It also regulates cell apoptotic signaling and enhances antioxidant activity. In conclusion, LC shows promise in treating several psychiatric and neurological disorders, but its efficacy varies across different conditions. Further research is needed to confirm its benefits and to explore its mechanisms of action in more detail.