Forests provide many essential ecosystem services. In Sweden, roundwood assortments and residual biomass are vital feedstock sources. Swedish forestry is slowly replacing conifer monocultures with mixed conifer-broadleaf forests to enhance climate resilience. This study evaluates the economic returns of managing mixed forest stands comprising 0.25 ha patches of individual species compared to larger Norway spruce and silver birch monocultures. Specifically, we investigate (1) harvesting silver birch as energy biomass in the first thinning and timber in the final felling and (2) determining thinning timing based on stand basal area versus species-specific criteria. We used the Heureka forest growth and development modelling software to simulate various stand types and management strategies based on experimental forest data. Group-mixed stands were simulated by integrating separate species’ monoculture data. Results indicate that incorporating energy thinning into birch-spruce mixed stands can generate positive net revenues, supporting the economic viability of biomass harvesting. Strengthening birch biomass and timber markets, optimising thinning logistics, and refining harvesting methods will promote sustainable birch management. Expanding these strategies could significantly enhance the economic and ecological resilience of mixed and broadleaf-dominated forests in Sweden.