Background: Despite the burden of tuberculosis (TB) in children, limited data are available on the impact of pulmonary TB (PTB) on lung function. We aimed to assess the impact of PTB on lung function and longitudinal trends following completion of TB treatment in children. Method: This analysis was nested in a prospective cohort study of children aged 0-13 years presenting with presumptive PTB who were able to perform spirometry. After comprehensive TB investigations and HIV testing, children were classified as TB cases (confirmed and clinically diagnosed), symptomatic controls (TB diagnosis excluded), and healthy controls. Spirometry was completed at baseline (at or within 8 weeks of enrolment) and follow-up (24 to 52 weeks after enrolment), included forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) in z-scores, using Global Lung Initiative reference ranges. Results: A total of 117 children were included, median age 6 years (interquartile range 5-9), 56% male, 23% HIV exposed and 8% living with HIV. Longitudinal analysis showed that FEV1 and FVC z-score at baseline significantly lower for children with PTB (n=29) compared to healthy controls(n=34) with a difference of -0.85 z-score (95% confidence interval (CI) -1.59- -0.12, p=0.02) and -0.84 z-score (95% CI -1.61- -0.07, p=0.03), respectively. Lung function tracking of TB cases showed there was minimal improvement of FEV1 and FVC over time. Conclusion: This study showed significant differences between lung function in children with PTB compared to healthy controls with minimal improvement over time even after TB treatment completion. There is an urgent need to obtain more long-term data on post-TB lung disease in children.