This work addresses the cost optimization of integrated absorption refrigeration and seawater thermal desalination systems. A double-effect water-lithium bromide absorption refrigeration system and a multi-effect evaporation process are proposed to satisfy given values of refrigeration capacity and fresh water production from seawater, respectively. A nonlinear mathematical programming (NLP) model of the integrated system is developed in the General Algebraic Modelling System (GAMS) platform in order to optimize the operating conditions and size of each process component. The minimization of the specific total annual cost is proposed as single optimization criterion. The optimal values of the composition, temperature, pressure, and flow rate of all streams (refrigerant, weak and strong solutions, seawater, discharge brine, and distillate) are obtained at the same time together with the corresponding heat transfer area of each process component. The coupling of both processes is through the refrigerant streams obtained in the low- and high-temperature generators, which are used as a heating utility in the multi-effect desalting system. The optimization problem is solved for several levels of refrigeration capacity in order to identify the freshwater production rate that can be obtained – for each refrigeration capacity – accounting for the operating and capital costs associated with the integrated system. The obtained solutions are discussed in detail.