In semi-arid regions where climatic limitations hinder open-field vegetable production, greenhouse-based lettuce (Lactuca sativa L.) cultivation plays a vital role in ensuring off-season supply. In this study, the potential of sustainable input combinations was evaluated to enhance lettuce productivity, quality, and profitability under unheated greenhouse conditions in Southeastern T & uuml;rkiye. Treatments included farmer practice and a mycorrhizal biofertilizer (ERS, a water-soluble arbuscular mycorrhizal fungus product) applied alone or in combination with organic-based biostimulants (IS and NM). Evaluated parameters were plant height, leaf pigmentation (a*, h degrees), SPAD values, vitamin C, nitrogen and phosphorus content, and gross margin. The ERS2+IS&NM treatment significantly enhanced plant height (32.5 cm), vitamin C content (28.63 mg 100 g-1 FW), and gross margin ($616.09 da-1), along with improved nutrient uptake and leaf coloration. These findings highlight the synergistic benefits of integrating mycorrhizal inoculants with organic-based biostimulants in greenhouse-grown lettuce systems. The results contribute to the development of eco-friendly, climate-resilient production strategies for protected cultivation in semi-arid environments.