Various hybrid desalination systems have been proposed during the last two decades to improve the produced water quality, energy efficiency, water production rate and sustainability among others, receiving therefore a rapid industrial implementation. Desalination processes are energy intensive and this energy is mostly provided by fossil fuels, especially for large scale commercial plants. No doubt, the use of renewable energy (RE) sources is a way forward to decrease the environmental and related health impact to produce and supply freshwater in remote regions with severe water shortage and an unfavourable or unfeasible connection to the public electrical grid. However, most installed renewable energy desalination plants have small capacities, yet facing several issues for long term operation. Therefore, this study restricts to the use of fossil fuel based energy source for desalination and provides a thorough analysis summarising the design, operation, and performance, techno-economic and associated challenges of hybrid seawater desalination systems based on several experimental/real plant and simulation studies reported since 2000. It includes mature membrane-based and thermal-based desalination technologies, namely Reverse Osmosis (RO), multistage flash (MSF), and multi-effect distillation (MED), and a number of emerging hybrid membrane-thermal water desalination technologies. Future opportunities in hybrid systems, including RO/MSF and RO/MED are also highlighted.