Prolonged droughts and subsequent river flow variations have reduced Brazil's hydropower output, creating a critical energy supply gap. To maintain grid reliability amidst the inherent variability of solar and wind expansion, electricity generation matrix has increased its dependence on environmentally detrimental alternatives. Although bioelectricity in Brazil is predominantly sourced from sugarcane, a substantial portion of the country's biomass potential remains underutilized. This study quantifies the theoretical, technical, and economic potentials of untapped biomass sources, including dedicated energy forests, crop residues, forest residues, vinasse, animal manure, municipal solid waste and excess electricity generation from the sugar industry, and assesses their integration into Brazil's future electricity mix from 2023 to 2050 using the Low Emission Analysis Platform (LEAP). Two energy scenarios were modelled, Business-As-Usual (BAU) and Available-Potential-Scenario (APS), which fully utilize the calculated economic potential. Results show that the economic potential of bioenergy could increase from 599.86 PJ in 2023 to 1455.27 PJ by 2050, supporting up to 70 GW of installed capacity. Under the APS, the renewable share in electricity generation increases from 87% (BAU) to 95% by 2050, with bioenergy contributing up to 26% of total electricity generation. This transition boosts energy availability by 42% compared to BAU and increases total installed capacity by 62% relative to the base year. Investment analysis showed that the additional installed bioenergy capacity does not create an investment burden, but rather reallocates capital toward cleaner energy alternatives. This research provides a practical strategy for Brazil to achieve its emissions reduction goals in electricity generation.