Water scarcity has a profound impact on crop yield and productivity, affecting numerous crop plants globally. Flax, a versatile crop with high nutritional value, is an essential oil seed and fiber crop. To combat drought stress, plants employ various mechanisms, and glycinebetaine (GB) plays a vital role as a compatible solute, mitigating stress through osmotic adjustment and membrane protection. A pot experiment was conducted at the Old Botanical Garden, University of Agriculture, Faisalabad, to investigate GB's role in flax under water stress. Two flax varieties, Roshini and Chandini, were subjected to two drought stress levels (controlled and 50% FC) and four GB levels (non-soaked, water-soaked, 10, and 20 mM) via pre-soaking seed treatment for 8 hours. Twenty seeds of each variety were sown in plastic pots, and a CRD design with four replicates was used to arrange the experiment. The results showed that drought stress significantly hampered morphological attributes, including shoot fresh weight, shoot length, and reduced chlorophyll pigments (chlorophyll a, b, total chlorophyll, and carotenoids). However, drought stress increased reactive oxygen species (ROS) like MDA and H2O2, triggering a response in enzymatic antioxidants (CAT, SOD, and POD). Exogenously applied GB as osmolytes enhanced shoot fresh weight, shoot length, and chlorophyll pigments (except chl a/b ratio), increased enzymatic antioxidants, and decreased ROS. Yield attributes were significantly improved, the Chandini variety performed better under stress conditions and 20 mM GB showing the best results in pre-soaking seed treatment.