The aim of the present study was to examine parental experiences of homeschooling during the COVID-19 pandemic in families with or without a child with a mental health condition across Europe. The study included 6720 parents recruited through schools, patient organizations and social media platforms (2002 parents with a child with a mental health condition and 4718 without) from seven European countries: the UK (n = 508), Sweden (n = 1436), Spain (n = 1491), Belgium (n = 508), the Netherlands (n = 324), Germany (n = 1662) and Italy (n = 794). Many parents reported negative effects of homeschooling for themselves and their child, and many found homeschooling to be of poor quality, with insufficient support from schools. In most countries, contact with teachers was limited, leaving parents with primary responsibility for managing homeschooling. Parents also reported increased levels of stress, worry, social isolation, and domestic conflict. A small number of parents reported increased parental alcohol/drug use. Some differences were found between countries and some negative experiences were more common in families with a child with a mental health condition. However, differences between countries and between families with and without a mental health condition were generally small, indicating that many parents across countries reported negative experiences. Some parents also reported positive experiences of homeschooling. The adverse effects of homeschooling will likely have a long-term impact and contribute to increased inequalities. Given that school closures may be less effective than other interventions, policymakers need to carefully consider the negative consequences of homeschooling during additional waves of the COVID-19 pandemic and future pandemics.