<p>Forest restoration is one of the most promising and powerful approaches to tackle the grand challenges of climate change and biodiversity loss. However, translating the growing global momentum for forest restoration into concrete biodiversity gains has remained elusive. In this Review, we describe the reforestation approaches and forest restoration methods currently used and how they affect biodiversity; summarize the current evidence, main determinants and knowledge gaps of biodiversity outcomes of forest restoration; and describe the emerging opportunities for planning, financing and monitoring biodiversity-centred forest restoration. We conclude with recommendations on why, where, how and for whom to restore forests while co-producing knowledge to sustain effective, long-lasting positive effects for biodiversity. Biodiversity is usually favoured by ecological restoration, especially through natural regeneration and in less disturbed conditions, yet the predominant focus on trees has held back broader effects across multiple taxa and biodiversity dimensions. Harnessing emerging funding opportunities and realizing the biodiversity benefits of forest restoration will require defining clear restoration goals and objectives pertaining to biodiversity in both policy frameworks and individual projects, using appropriate restoration strategies and approaches, implementing adequate monitoring and disclosure of results and ensuring mechanisms for sustained funding.</p>