The paper examines gender income inequality of informal workers in the context of the COVID-19 pandemic in Vietnam through Theil’s L index, using the Labor Force Survey by the General Statistics Office of Vietnam for the first three quarters of 2021. It is indicated that gender income inequality triggers informal workers’ income inequality. Furthermore, males are proven to contribute more to income inequality among informal workers. In addition, after utilizing the Blinder-Oaxaca decomposition method, it is found that personal, labor-employment and geographical characteristics are factors breeding informal workers’ gender income inequality. Based on the findings, the authors propose several suggestions to equilibrate their income distribution and lessen the gender income inequality of informal workers.