<p>Among pregnant women, influenza increases the risk of complications such as hospitalization, intensive care unit admission, and death. To prepare for new pandemics in the future, pregnant women’s perceptions of influenza vaccines during the COVID-19 pandemic should be investigated. This study used the theory of planned behavior (TPB) to identify the determinants of pregnant women’s intention to receive the influenza vaccine and their uptake of it during the COVID-19 pandemic. A cross-sectional study was conducted among pregnant or postpartum women within one year of delivery from the largest online panel (n = 351). Data were collected using an online survey during April 1–15, 2022. Path analysis was performed to investigate the pathways of the TPB constructs’ effects on influenza vaccine uptake. The influenza vaccination rate among pregnant women during the pandemic was 51%. Attitude towards vaccine (β = 0.60, <i>p</i> &lt; 0.001) and subjective norms (β = 0.28, <i>p</i> &lt; 0.001) directly and positively affected intention, which directly and positively affected uptake (β = 0.48, <i>p</i> &lt; 0.001). Attitude towards vaccine (β = 0.29, <i>p</i> = 0.006) and subjective norms (β = 0.134, <i>p</i> = 0.015) also positively and indirectly affected uptake. Influenza vaccine uptake remains suboptimal among pregnant women in many countries. Attitude towards vaccine is the strongest determinant of the intention to receive the vaccine and its uptake during pregnancy. More active efforts are required to improve pregnant women’s attitudes toward the vaccine.</p>