Introduction: L-carnosine has been found to have multimodal activity. Aim: The aim of this review was to find out the efficacy of L-carnosine in patients with age-related diseases. Methods: Clinical studies evaluated the effect of L-carnosine on cancer, cardiovascular disease, diabetes, and neurodegenerative disorders were searched in electronic bibliographic databases. The protocol has been registered with PROSPERO (CRD42022314033). The revised Cochrane risk of bias tool for randomized trials was used to assess all of the reports for risk of bias. RevMan 5.4 was used to conduct the meta-analysis. Results: Following the screening process, 14 papers were selected for systematic review, with 9 of them being qualified for meta-analysis. Many of the included studies showed that L-carnosine has potential therapeutic activity in age related diseases. Results from the meta-analysis showed that in diabetes mellitus, HbA1c [mean difference (MD) 95% CI = –1.25 (–2.49, –0.022); p = 0.05; p = 0.001; I{}^2 = 85%] and fasting blood sugar (FBS) [MD 95% CI = –12.44 (–22.44, –2.44); p = 0.01; p = 0.40; I{}^2 = 0%] and in neurodegenerative disorder, Wechsler Memory Scale Logical Memory 2 (WMS-LM2) [MD 95% CI = 1.34 (0.83, 1.85); p 0.00001; p = 0.43; I{}^2 = 0%], showed statistically significant difference, favoring the L-carnosine group over the control group. While in neurodegenerative disorder, Alzheimer ’s Disease Assessment Scale (ADAS) [MD 95% CI = 0.98 (–1.55, –0.42); p = 0.0007; p = 0.86; I{}^2 = 0%] and Back Depression Inventory (BDI) [MD 95% CI = –1.12 (–1.87, –0.37); p = 0.003; p = 0.73; I{}^2 = 0%] showed statistically significant difference, favoring the control group over L-carnosine group. Conclusions: Clinical studies were conducted to manage chemotherapy induced toxicities and there are no clinical studies available for its anti-cancer use, and the current evidence does not support its use in the treatment of cardiovascular disease.