Background <p>Weight reduction is a common clinical feature observed in patients with colorectal cancer and often reflects underlying tumor burden or nutritional status. This meta-analysis aims to systematically synthesize existing evidence on the relationship between weight loss and survival outcomes in patients with colorectal cancer.</p> Methods <p>An exhaustive literature search was conducted in PubMed, Embase, and Web of Science, covering all records from the inception of each database through May 15, 2025. Inclusion criteria focused on studies reporting quantitative associations between weight loss and overall survival, progression-free survival, and colorectal cancer–specific mortality in patients with colorectal cancer. For the meta-analytic synthesis, adjusted hazard ratios (HR) with 95% confidence intervals (CI) were pooled using a random-effects model.</p> Results <p>Thirteen eligible studies involving 17,606 colorectal cancer patients were identified. Pooled estimates derived from random-effects modeling indicated that weight loss was significantly associated with shorter overall survival (HR 2.02; 95% CI 1.67–2.44) and progression-free survival (HR 1.34; 95% CI 1.14–1.58). Additionally, weight loss was linked to an increased risk of colorectal cancer–specific mortality (HR 3.27; 95% CI 1.75–6.12). Subgroup analyses revealed notably reduced overall survival among patients aged over 60 years (HR 2.94; 95% CI 2.45–3.53) and those experiencing weight loss of 10% or more (HR 3.19; 95% CI 2.58–3.93), compared to their counterparts.</p> Conclusions <p>Weight loss is a significant and independent prognostic indicator of reduced survival in patients with colorectal cancer. Further rigorous prospective studies are needed to confirm these findings and to investigate the potential underlying biological mechanisms.</p>