Background: Asthma is a heterogeneous disease characterized by chronic airway inflammation with a rising prevalence globally, and its aetiology has been linked to vitamin D (VD) deficiency. Aim: This study aimed to determine the serum VD levels and its relationship with asthma control and severity among asthmatic children in UDUTH, Sokoto, Nigeria. Materials and methods: This was a cross-sectional study among 60 asthmatic children selected by systematic sampling technique. Data were collected with a proforma; anthropometric measurements, estimation of serum VD levels, and assessment of lung function were done. Results: The median age of the asthmatic children was 9.47 years (IQR = 3.98) and majority of them (58.3%) were males. The median serum VD level was 16.25 ng/ml (IQR = 13.38), and about two-thirds of the participants (63.3%) were VD deficient. A half of the participants 30 (50.0%) had well-controlled asthma, 21 (35.0%) had partly-controlled asthma, while 9 (15.0%) had uncontrolled asthma. There was no relationship (p > 0.05) between the serum VD levels and asthma control. Almost all the participants (98.3%) had mild to moderate asthma, and majority of them (66.7%) had intermittent or mild persistent asthma. There was no relationship (p > 0.05) between the serum VD levels and asthma severity. Conclusion: Although VD deficiency was very prevalent among the participants, there was no relationship between the serum VD levels and asthma control and severity. There is need to prevent and control VD deficiency in the study population through VD supplementation, food fortification and promotion of adequate exposure of children to sunlight by mothers.