Respiratory syncytial virus associated acute lower respiratory infection (RSV-ALRI) constitutes a substantial disease burden in young children. We aimed to identify all studies investigating the risk factors of RSV-ALRI poor outcome or mortality in young children. We carried out a systematic literature review across 7 databases with data from studies published from January 1995 to December 2019. We defined poor outcome as need for prolonged hospital stay, oxygen supplementation, mechanical ventilation or intensive care unit (ICU) admission. Quality of all eligible studies was assessed according to modified GRADE criteria. We conducted meta–analyses to estimate odds ratio (OR) with 95% confidence intervals (CI) for individual risk factors. We identified 27 eligible studies, which investigated 20 risk factors for RSV-ALRI poor outcome and/or mortality in children younger than 5 years old, in comparison to those with RSV-ALRI who did not have poor outcome or mortality. Among those risk factors, 6 had statistically significant associations with RSV-ALRI poor outcome: any comorbidity (OR 2.69 (95% CI 1.89-3.83)), congenital heart disease (3.40 (95% CI 2.14-5.40)), prematurity with gestational age (GA) <37 weeks (1.75 (95% CI 1.31-2.36)), prematurity with GA ≤32 weeks (2.68 (95% CI 1.43-5.04)), age <3 months (4.91 (95% CI 1.64-14.71)), age <6 months (2.02 (95% CI 1.73-2.35)). Apart from age <3 months, the meta-estimate ORs for all other risk factors were based on studies using multivariable analysis. For mortality, only prematurity with GA <37 weeks had a significant meta-estimate of OR 3.81 (95% CI 1.68-8.63) based on univariable analysis. This study represents a comprehensive report of the association between various risk factors and RSV-ALRI poor outcome and mortality in young children. More research should be carried out to elucidate risk factors associated with poor outcome and mortality using multivariable analysis.