The increasing carbon emission, global energy demand, and depleting fossil fuels have compelled to search for other promising alternatives such as renewable sources; solar energy, wind energy, or solid waste (SW). The discarded SW can be used as an energy source and can participate in the growth and economic development of the world economy. The major advantages of utilizing SW is its potential sustainability, lower processing cost, easy availability, lower carbon emission than fossil fuels, and achieves high conversion. However, major issues associated with SW are mainly volume consumption and release of hazardous gases. Thus, proper pre-treatment is required prior to its direct utilization in thermal application sectors, without any bargain with the environment and public health. The present study highlights the waste-to-energy technologies existing till date. It has been observed that 90% of the SW is treated with pyrolysis or incineration technology in the worldwide scenario which have few drawbacks like air and waterborne pollution. Gasification minimizes the solid waste mass up to 70% and the volume by 90%. Plasma pyrolysis and plasma gasification produces 90% of combustible gases but it requires enormous energy (2.88–3.12 MJ/kg of solid waste). The detailed discussion of each process is provided highlighting their merits and demerits of each WTE technologies. Thus, in this chapter author is also trying to provide best suitable waste-to-energy treatment technologies (WTE-T) based on composition, quality and quantity of SW.