Forest recovery is central for addressing major sustainability challenges, such as climate change and biodiversity loss. While positive assessments prevail over the global ecological forest restoration potential, critical research highlights limited potentials and even detrimental local impacts, particularly in the Global South. Here, we argue that knowledge integration across land system science (LSS) and political ecology (PE) can contribute to addressing this contradiction and advance knowledge about ecologically sustainable and socially just forest recovery. We identify five key areas where knowledge integration is promising: (1) developing multidimensional forest definitions, (2) linking forest land to users and interests, (3) identifying reforestation failures and successes, (4) associating drivers and impacts across places and scales, and (5) including justice dimensions in assessments of socio-ecological forest recovery potentials. For each knowledge area, we review key contributions by LSS and PE, and outline future research directions to address ecologically sustainable and socially just forest recovery.