This paper presents a critical parameter driven optimum conceptual design of an ultra-low motion semisubmersible floating oil and gas production system. The design is carried out to satisfy the given parameter of weights and dimensions of the platform topsides required for production and drilling, water depth location, and low motion requirements. The proposed design process is highly iterative process of altering the key dimensions of a 'n-column ring' pontoon, and it meets applicable regulations and customer requirements while minimizing costs and satisfying the chosen parameters. The chosen parameters are classified into groups depending upon the scientific and technological requirements, and they are: GAaOHD - general arrangement and overall hull design, WaCL - wind and current loading, LaGL - local and global loading, WBS - weight/buoyancy/stability, HMaL - hydrodynamic motion and loading, SaSD - strength and structural design, M - mooring, and EaC - economics and cost. Overall, this paper introduces a novel design process for an ultra-low motion semi-submersible that covers the complete life cycle of the structure. Finally, it has been discussed one design example motivated by real world applications to show the effectiveness, usability and efficiency of the proposed model.