The Minato Mirai 21 District in Yokohama is developing an innovative urban decarbonization model through public-private collaboration, addressing and overcoming challenges unique to densely developed urban areas. The district is advancing a range of initiatives, including the introduction of renewable electricity sourced both within and outside the area, the decarbonization of heating and cooling through the district energy system, and the promotion of resource circulation tailored to the specific characteristics of an urban district where hotels, commercial facilities, and other large-scale developments are concentrated. This presentation will introduce the background of these initiatives, the measures being implemented, and the achievements attained to date.