ABSTRACT Physical activity during pregnancy has numerous health benefits for the woman and the foetus. The current study investigated physical activity engagement and its predictors among pregnant Chinese women during the first trimester. A total of 687 pregnant women completed the Pregnancy Physical Activity Questionnaire. Bivariate and multivariate logistic regression were used to analyse the data. The current physical activity guidelines were not met by 64.3% of respondents. Women with higher levels of physical activity self-efficacy (aOR = 0.96; 95% CI: 0.92–0.99) and social support (aOR = 0.95; 95% CI: 0.94–0.97) had lower odds of not meeting the current physical activity guidelines. Women who were aged < 35 years (aOR = 1.85; 95% CI: 1.02–3.34), had lower education (aOR = 1.63; 95% CI: 1.04–2.55), were primiparous (aOR = 11.03; 95% CI: 6.98–17.44), were unsure of their delivery mode (aOR = 2.32; 95% CI: 1.95–5.64), and those who had higher levels of pregnancy-associated discomfort (aOR = 1.10; 95% CI: 1.03–1.19) had higher odds of not meeting the current physical activity guidelines. The current study suggests that healthcare professionals should assess physical activity engagement during routine antenatal care and increase efforts to strengthen pregnant women’s self-efficacy and social support to promote physical activity engagement during the first trimester.