The key challenge of dual fuel mode (DFM) of a compression ignition (CI) diesel engine is to improve the engine performance, and to reduce primarily the carbon monoxide (CO) and unburnt hydrocarbon (HC) emissions. The gaining popularity of DFM lies with its inherent ability to curb harmful pollutants, besides offering operational flexibility to use gaseous and liquids fuels simultaneously. In addition, the use of renewable fuels in DFM is found to be highly suitable to achieve the optimum engine overall performance. In this DFM study, biogas as the primary gaseous fuel is used in a diesel engine in conjunction with ternary blends of diesel-biodiesel-ethanol (TB-E), diesel-biodiesel-butanol (TB-BT), and diesel-biodiesel-diethyl ether (TB-DEE) as the renewable pilot fuels. For each combination, the experiments are conducted at the optimum global fuel–air equivalence ratio (Φglobal) and with intake charge preheating to analyze the performance, combustion and emission characteristics of the engine. The important parameters such as brake thermal efficiency, actual diesel replacement, coefficient of variation of indicated mean effective pressure, relative cycle efficiency, cylinder mean gas temperature, ignition delay, and combustion duration are investigated. The study demonstrates the optimum performance of the DFM engine with TB-DEE.