INTRODUCTION: Although caring for a child with intellectual and developmental disabilities (IDD) can have positive outcomes, parents may be at a greater risk of depression and anxiety, due to a number of associated stressors, such as increased caregiver demands and financial strain. This systematic review updates previous data, exploring the relationship between parenting a child with IDD and parental depression and anxiety. METHODS: Five electronic databases were searched for eligible English-language articles, published between January 2004 and July 2018. All epidemiological study designs were eligible, provided the level of depression and/or anxiety was compared between parents of children (aged <18) with and without IDD. No limit was placed on geographic location. The proportion of positive associations between parenting a child with IDD and depression/anxiety were disaggregated by disability type, geographic region, and sample size. The percentage of parents at risk of moderate depression or anxiety were calculated using recognised clinical cut-off scores for each screening tool. Meta-analyses, in which pooled effect sizes of elevated depression and anxiety symptoms were calculated, were conducted across two IDD conditions, autism and cerebral palsy. RESULTS: Of the 5,839 unique records screened, 19 studies fulfilled the inclusion criteria. The majority of studies were conducted in high-income (n = 8, 42%) or upper-middle income countries (n = 10, 53%). Of the 19 studies, 69% focused on parents of children with cerebral palsy (n = 7, 37%) or autism (n = 6, 32%). Nearly all studies found a positive association between parenting a child with IDD and depression (n = 18, 95%) and anxiety (n = 9, 90%) symptoms. Factors associated with higher levels of depression symptoms amongst parents of children with IDD included disability severity (n = 8, 78%) and lower household income (n = 4, 80%). Approximately one third (31%) of parents of children with IDD reach the clinical cut-off score for moderate depression, compared with 7% of parents of children without IDD. 31% of parents of children with IDD reach the cut-off score for moderate anxiety, compared with 14% of parents of children without IDD. The meta-analyses demonstrated moderate effect sizes for elevated depression amongst parents of children with autism and cerebral palsy. CONCLUSIONS: Results indicate elevated levels of depressive symptoms amongst parents of children with IDD. Quality concerns amongst the existing literature support the need for further research, especially in low- and middle-income countries.