The method of recycling brine from a multi-stage flash desalination plant recycles the high-salinity, high-temperature brine output from a multi-stage flash desalination plant to produce diluted brine suitable for reinjection back into the multi-stage flash desalination plant as a makeup stream. The high-salinity, high-temperature brine output from the multi-stage flash desalination plant is diluted with water extracted from treated wastewater effluent output from a wastewater treatment plant, thus providing further recycling of the treated wastewater effluent. Following osmotic transfer of the diluting water from the treated wastewater effluent to produce the diluted brine, the remaining concentrated treated wastewater effluent passes through a secondary filtration system to yield a solid product and a volume of permeate water. The volume of permeate water may be further mixed with the diluted brine.