Combining crops and livestock within integrated crop–livestock systems (ICLS) represents an opportunity to improve the sustainability of farming systems. The objective of this paper is to analyse how agroecological principles can help farmers to redesign and improve the resilience, self-sufficiency, productivity, and efficiency of ICLS. Relying on case studies from Brazil and France, we examine how the transformation of two conventional, specialised systems into more integrated-production systems illustrates the different dynamics towards agroecological ICLS. The French case study, based on self-sufficient farming systems belonging to a sustainable agriculture network, highlights that cost-cutting management led to a win–win strategy comprising good economic and environmental performances. The farms decreased their dependence on external inputs and had only a limited loss of production. The past trajectories of the farms illustrate how increasing the interactions between subsystems improved the self-sufficiency and efficiency of the farms. The Brazilian case study compares slash-and-burn agriculture in the Amazonian region with the recovery of degraded grazing area by ICLS. A small increase in chemical inputs linked to a diversification of productions led to a large increase in production and a large decrease in environmental impacts (deforestation). The Brazilian case study also illustrates how the diversification of production increased the resilience of the system to market shocks. Reconstructing the links among soil, crops, and animals following agroecological principles could improve the different performances of ICLS. New agroecological ICLS, benefiting from diversified productions and increased interactions between subsystems, are likely to offset the trade-off between agricultural production and environmental impacts observed in current ICLS.