Background <p>Pregnancy triggers physiological adjustments through hormonal changes, supporting foetal growth and preparation for labour. Becoming more pronounced with excessive weight, these changes may trigger pathophysiological changes and unmask pre-existing disease conditions. In developing countries, many pregnant women experience either inadequate or excessive weight gain and may present with perturbed metabolism. Lifestyle interventions, including regular physical activity, are important but often overlooked in these settings. Context-specific data on physical activity and cardiometabolic profile of overweight and obese pregnant women are limited in sub–Saharan Africa, specifically Tanzania. The current analysis aimed to determine the relationship between pre-pregnancy overweight/obesity, pregnancy physical activity and cardiometabolic factors among pregnant women.</p> Methods <p>This cross-sectional study involving 243 pregnant women aged 18–35 was conducted in selected antenatal clinics in Dodoma, of whom 37% (<i>n</i> = 91) were overweight or obese. The current analysis assessed physical activity, anthropometric, and cardiometabolic parameters and compared between overweight/obese and normal-weight participants.</p> Results <p>Overweight and obese pregnant women demonstrated significantly lower levels of physical activity across various domains, including overall physical activity (<i>p</i> &lt; 0.001) and median METs (metabolic equivalent of tasks) minutes per week (<i>p</i> &lt; 0.001) compared with their normal weight counterparts. In particular, they had lower median METs obtained from the occupational domain (<i>p</i> = 0.037). Additionally, the same group engaged less in exercise or leisure time physical activities (<i>p</i> = 0.014), with a lower percentage of contribution to total METs minutes per week obtained from these activities (<i>p</i> = 0.002). Furthermore, overweight or obese participants exhibited higher systolic blood pressure (<i>p</i> &lt; 0.001), diastolic blood pressure (<i>p</i> = 0.008), haemoglobin levels (<i>p</i> &lt; 0.001), fasting blood glucose levels (<i>p</i> = 0.005), serum triglycerides levels (<i>p</i> = 0.012), and total cholesterol levels (t(234) = 1.98, <i>p</i> = 0.048) than their normal–weight counterparts.</p> Conclusion and recommendations <p>Overweight and obese pregnant women showed lower physical activity levels, with low levels of both occupational and leisure time (exercise) physical activities, possibly explaining the observed cardio metabolic perturbation in this group. An intervention aiming at promoting physical activity and enhancing cardiometabolic health among this group is necessary.</p>