Aims: Gastrostomy feeding represents a vital component of supportive care provided to people with swallowing or feeding difficulties; however, the rate of specific long-term complications is currently unknown in the adult population. This study aimed to determine the prevalence of specific long-term gastrostomy-related complications and unplanned replacements in adults. Methods: A prospective systematic review of Medline, CINAHL and Embase databases was performed. Key complications of hypergranulation, infection and displacement among studies relevant to percutaneous endoscopic gastrostomy tubes, radiologically inserted gastrostomy tubes and balloon replacement tubes were critically appraised by two independent reviewers. Results were synthesised quantitatively in a meta-analysis using random effects where the population and condition were sufficiently homogeneous. Results: In total, 453 studies were identified, of which 17 met inclusion criteria. 8.5% of adults with a gastrostomy were found to have had an infection ≥42 days after initial tube insertion (p < 0.01), while 13% had hypergranulation (p < 0.01). Displacement occurred in 10.8% of adults (p < 0.01), with age (p < 0.001) and sex (p < 0.001) presenting as a risk factor (R2 = 75%) following meta-regression. Conclusions: Approximately 1 in 10 people with a gastrostomy will experience a complication related to either hypergranulation, infection or dislodgement. Age, in combination with sex, may provide a guide for risk of displacement among adult female cohorts, though further studies reporting prevalence of gastrostomy-related complications along with participant demographics are required.