Background Endoscopic septoplasty has become the preferred choice for septal surgeries for most surgeons due to its precise manipulation and reduced wear and tear. However, the improvement of the airway may vary depending upon the type of septal deviation the patient presents with. Cottle in 1946 stated that just mere dealing with deviated septum alone would not ensure a good functional outcome and he further emphasized on addressing portions of the nose obstructing nasal airflow during surgery. The purpose of our study is to subjectively and objectively assess the effectiveness and corrective extent of endoscopic septal correction in different types of septal deviations (Mladina classification) using NOSE scores and Peak Nasal Inspiratory Flowmetry (PNIF). A prospective cross-sectional study was conducted in 87 patients presented in our department from July 2021 to June 2022 for endoscopic septoplasty. Results Post-surgery 1-month follow-up (N1), the correction in terms of NOSE scores was highest in Mladina IV and least in Mladina I deviations, and at the end of 3 months (N2), the correction was best recorded in Mladina VI deviations while the least remained in Mladina I. Similarly, PNIF 1-month follow-up (P1) result had the best correction in the Mladina IV and V groups with the least in Mladina I. 3 months of follow-up (P2) ended up showing a maximum improvement in the Mladina VI group. Paired t test values for improvement of NOSE and PNIF scores were significant ( p value < 0.001) between preoperative, 1-month, and 3-month follow-up values and also for repeated measure ANOVA. Conclusion Our study reveals that the corrective power of endoscopic septoplasty differs with respect to different types of septal deviation in terms of nasal airflow, both subjectively and objectively. Thus, proper counseling and preoperative assessment is essential for better postoperative outcome and compliance.