This study aims to establish baseline data for sustainable monitoring by applying the green city index (GCI), which is set up to evaluate the city level, to the city of Gangneung-si, which was designated as a pilot city for the Low-carbon Green Growth City project by the Ministry of Land, Infrastructure, and Transportation. The GCI was applied in the framework of European systems, while considering the social and economic status of Korea. Indicators from 7 areas—CO2, energy, building, transportation, water, waste, and quality of atmosphere were analyzed, except for qualitative indicators. Results indicate that total CO2 emissions were 30.8 tons per capita, or 2.2 tons per one million units of real GDP. The total final energy consumption was 0.231 TOE/capita, or 0.317 TOE per one million units of real GDP. The percentage of total energy derived from renewable resources was 0.41% and energy consumption by the building was 433.5 Mwh/1,000 ㎡. The total percentage of the working population travelling to work daily by public transportation (limited to bus) was 19%. Further, the total annual water consumption was 99 ㎥/capita, and the water lost in the water distribution system was 0.057 ㎥/capita/day. The total annual waste collected was 0.0077 ton per capita, The annual mean emission were 0.014 ppm/day for NO2, 0.005 ppm/day for SO2, and 0.019 ppm/day for O3. The annual mean for PM10 emissions was 39 ㎍/㎥/day.