For a long time, engineering design research has been focused on the development of various design theories, methodologies, methods, tools, and procedures. The design methods have been subsequently used by engineers to more efficiently design artifacts. However, as the artifacts have grown in complexity, the need for new methods has become obvious. Also, in a nowadays world, increased competition and globalization require organizations to reexamine traditional product development strategies. Traditional methods focused exclusively on the numerical optimality of produced artifacts, or their manufacturing proceses, are no longer adequate. Creativity and innovation of designed artifacts provide organizations not only with a competitive advantage but are, in fact, a matter of their survival. This dissertation addresses this problem by posing and answering the question: "How can one construct an effective method for designing engineering systems that would support development of novel/creative design and their efficient optimization?" It proposes a new and conceptually coherent design method, called Emergent Engineering Design. The proposed design method is inspired by the fundamental processes occurring in nature, which has arguably created the most fascinating designs known to humankind. All major phases of Emergent Engineering Design are represented by complex systems, including cellular automata and evolutionary algorithms, which have been successfully used to model the processes governing the complex behavior occurring in nature. In order to facilitate the development of the proposed design method, Emergent Engineering Design was implemented in a computer system called Emergent Designer. It is an integrated research and design support tool which applies models of complex systems to represent engineering systems and analyze design processes. Emergent Designer was used to conduct the empirical validation of the proposed design method for two classes of conceptual design problems in structural engineering. The extensive design experiments reported in this dissertation have shown that Emergent Engineering Design not only generates novel design concepts exhibiting remarkable structural shaping patterns but it also efficiently optimizes them.