This present work reports the combustion studies of coal, petroleum coke (PC) and biomass blends to assess the effects of the mustard husk (MH), wheat straw (WS), and flaxseed residue (FR) blending toward improvement of coal combustion characteristics. Ignition temperature (TS), maximum temperature (TP), burnout temperature (TC), activation energy (AE), and thermodynamic parameters (ΔH, ΔG, and ΔS) were analyzed to evaluate the impact of biomass and PC blending on coal combustion. Experimental results indicate that coal and PC have inferior combustion characteristics compared to MH, WS, and FR. With the increase in WS content in blends from 10 to 30%, TS reduced from 371 to 258 °C and TP decreased from 487 to 481 °C, inferring substantial enhancements in combustion properties. Kinetic analysis inferred that blended fuel combustion could be explained mostly using reaction models, followed by diffusion-controlled and contracting sphere models. Overall, with the increase in FR mass in blends from 10 to 30%, AE decreased from 108.97 kJ/mol to 70.15 kJ/mol signifying ease of combustion. Analysis of synergistic effects infers that higher biomass addition improves coal and PC blends’ combustion behavior through catalytic effects of alkali mineral matters present in biomass. Calculation of thermodynamic parameters signified that combustion of coal and PC is challenging than biomasses; however, blending of biomass makes the combustion process easier.