The present investigation entitled “ Evaluating the Effects of Bio-formulations and Boric Acid in Bael (Aegle marmelos )cv.NB-9 under subtropical condition” was carried out during the year 2022-2024 at Main Experimental Station, Department of Fruit Science, College of Horticulture & Forestry, A.N.D.U.A.&T., Narendra Nagar (Kumarganj), Ayodhya, Uttar Pradesh, India. The treatments comprised the application of various Bio-formulations and Boric acid with eco-friendly materials to study the various chemical properties, cracking, fruit drop and effect of the above treatments on the quality of fruit. The experiment was laid down in randomized block design (RBD) with (12) treatments and (03) replications. The experiment consists of 12 treatments including control, T1 (Control), T2 (FYM 50 Kg), T3 (FYM 100 Kg), T4 (Boric acid 200g), T5 (Boric acid 400g), T6 (Biofertilizer 250g/plant [100g Azotobacter + 100g Biovita + 50g PSB]), T7 (FYM 50Kg + Boric acid 200g), T8 (FYM 50Kg + Boric acid 400g), T9 (FYM 50Kg +Biofertilizer 250g/plant [100g Azotobacter + 100g Biovita + 50g PSB]), T10 (FYM 100Kg + Boric acid 200g), T11 (FYM 100Kg + Boric acid 400g) and T12 (FYM 100Kg +Biofertilizer 250g/plant [100g Azotobacter + 100g Biovita + 50g PSB]) was used for this study. The results revealed that the treatment T7 outperformed the rest with maximum TSS (36.27°B), minimum acidity (0.33%), maximum ascorbic acid (24.51 mg/100g), total sugar (20.29%) was most effective in chemical properties of Bael fruits like Total Soluble Solids (TSS), Vitamin C (Ascorbic acid), Reducing sugar, nonreducing sugar, Total sugars, and less acidity in quality point of view. Thus, the treatment combination T7 is therefore recommended for application to Bael trees in subtropical conditions to obtain high yields with better quality fruits