As the global population shifts towards an increasingly urban matrix, the importance of developing a robust system of biodiversity management on a city scale will continue to grow. Conventional urban design has led to considerable problems with ecological health and human well-being and is not suited to deal with pressing urban issues such as natural conservation, climate adaptation and mitigation, and ecosystem stewardship within planning and design. A more coherent blend of natural and built environments is possible, however, and provides mutual benefit. This review surveys the literature on urban ecosystems since 1994, utilizing currently accepted research on biodiversity, natural conservation, stewardship, management, and climate adaptation and mitigation in order to advance an ethic of best practices for cities and their biodiversity management goals.