It is innovative to account for the carbon dioxide equivalent (CO2e) of underdeveloped regions such as Nanning city of China. Meanwhile, the ‘Global Protocol for Community-scale greenhouse gas emission inventories (GPC)’ has been considered a worldwide comparable framework for calculating urban CO2e emission (CE). So, the CEs of Nanning were calculated during 1994–2015 by the GPC methodology in this paper. The results show the total CE of Nanning, containing the electricity CE of Scope 2, grew rapidly from 6.56 Mt in 1994 to 55.44 Mt in 2015, with an annual average increasing rate of 10.69% and amount of 2.33 Mt. The biggest three contributors were industrial energy consumption, transportation and industrial processes, which contributed 29.72–61.09, 10.75–41.87 and 7.40–14.99%, respectively, to the total CE. Almost always, more than 90.94% of Nanning’s CE was related to coal. When considering only the CEs from coal, oil and gas, both these CEs per unit area and per GDP of Nanning were always greater than those of the world, although less than those of China due to the underdeveloped status of Nanning in most years. So, it was necessary for Nanning to pursue the pattern of low-carbon development, and some corresponding countermeasures were recommended.