Ocimum gratissimum is an essential plant because of its wide food and medicinal usage. Despite its relevance, its morpho-physiological compositions are influenced by several abiotic stresses. Hence, this study examined the effects of water stress on the growth and chlorophyll contents of O. gratissimum. Seedlings of O. gratissimum were grown in twenty-four pots, two per pot and were arranged using a complete randomized design with four groups: Very Wet O. gratissimum (VWO), Moderately Water Stress O. gratissimum (MWSO), Strongly Water Stress O. gratissimum (SWSO) and Adequately Watered O. gratissimum (AWO) as control. Fifty centiliters of water was applied in AWO once daily, VWO twice daily, MSWO once in three days and SWSO once a week. Growth parameters: Stem height, number of leaves, leaf area, stem girth and petiole length were determined one week after treatment for six weeks. Chlorophyll contents were determined at two weeks intervals after treatment for eight weeks. Descriptive statistics such as mean±standard deviation and one-way Analysis of Variance (p < 0.05) were done using SAS software. Results obtained showed the highest mean stem height (27.50 ± 0.29 cm), number of leaves (37.00 ± 9.0), leaf area (735.7 ± 4.12 cm2), stem girth (0.40 ± 0.00 cm) and petiole length (7.20 ± 0.40 cm) in VWO. Similar results were obtained for chlorophyll (56.70 ± 0.65 mg–1). It could be concluded that regular watering of O. gratissimum could promote growth and increase chlorophyll contents of the plant.