The purpose of this paper is to investigate the implementation of green government spending as an effective instrument for enhancing both environmental sustainability and economic efficiency. Utilizing a model with two types of households examined in the optimal taxation literature, this paper analyzes the impact of green spending, the properties of optimal tax rates, and the optimal provision of the public good. We derive a modified greened version of the Samuelson rule, that is, the optimal provision of the public good in connection with environmental sustainability. Our results indicate that the overall effect of green spending measured in terms of government revenue is subject to several factors such as the influence of green spending on environmental sustainability, the cost of green spending, pollution effects, and so on. To determine the optimal provision of public goods, the aforementioned factors have to be taken into account. For instance, if the pollution effect is stronger, the individual marginal effective tax rate and the commodity tax rate on the polluting good will increase to discourage the demand for consuming polluting commodities.