Abstract Background Infections caused by influenza and COVID-19 during pregnancy represent a current public health problem as there are multiple populations at risk of complications: pregnant women, fetus, and future unborn children. The anatomical and physiological remodulation characteristic of pregnancy is responsible for the high pathological burden related to respiratory infections. Co-administration of influenza and COVID-19 vaccines may be beneficial because these two respiratory viruses cocirculate during cold weather. The need to explore pregnant women’s attitudes toward co-administration of influenza and COVID-19 vaccines and to evaluate factors associated with vaccine decision-making led to the conduct of this study. Methods In Palermo, Italy, during the 2021-2022 influenza season, a cross-sectional study was conducted to evaluate pregnant women’s intention to adhere to co-administration of influenza and COVID-19 vaccines. The determinants of vaccination attitudes were investigated through the administration of a questionnaire. The Health Action Process Approach theory (HAPA) was adopted to explore the cognitive behavioral aspects. Results Overall, 120 pregnant women were enrolled; average age 32 years, 98.2% (n = 118) of Italian nationality and 25.2% (n = 30) with obstetric or pathological conditions of pregnancy at risk. Factors significantly associated with attitudes toward co-administration of influenza and COVID-19 vaccines among pregnant women were: high level of education (OR = 13.96; p < 0.001), expectations of a positive outcome (OR = 2.84; p < 0.001) and self-efficacy (OR = 3.1; p < 0.001). Conclusions Vaccines co-administration could represent an advantageous preventive practice to facilitate vaccination logistics and allow full adherence to vaccinations recommended to pregnant women. Effective strategies to promote co-administration of influenza and COVID-19 vaccines could be focused on counselling about the expectation of positive outcomes of vaccine co-administration. Key messages • The need to explore pregnant women’s attitudes toward co-administration of influenza and COVID-19 vaccines and to evaluate determinants of vaccine decision-making led to the conduct of this study. • Vaccines co-administration could represent an advantageous preventive practice to facilitate vaccination logistics and allow full adherence to vaccinations recommended to pregnant women.