Mid-upper arm circumference (MUAC) has been recommended as an alternative indicator in the assessment of nutrition. The objective of the present study is to validate the feasibility of MUAC to determine both undernutrition and overweight obesity among reproductive women in Assam, Northeast India. The present cross-sectional study was undertaken among Mishing reproductively active women (n = 1,056) from flood-affected regions of Assam. The study participants were drawn using the stratified-random sampling method. Anthropometric measurements of weight, height and MUAC were collected, and body mass index (BMI) was calculated. The Asia-Pacific population BMI cut-offs were utilised to determine undernutrition and overweight obesity. The linear regression analysis showed significant variation between BMI and MUAC (R2 = 0.389; p < 0.01). Receiver operating characteristic (ROC) curve and Area Under Curve (AUC) showed that MUAC had significant predictive accuracy for undernutrition (AUC: 0.78), overweight (AUC: 0.77) and obesity (AUC: 0.88). The determination of severe undernutrition (AUC: 0.85) and moderate undernutrition (AUC: 0.81) strongly utilised for ROC-AUC analysis (p< 0.001). The derived cut-offs of MUAC were found to be ≤22.8 cm, >23.4 cm and >24.8 cm for undernutrition, overweight and obesity, respectively. The result indicates a strong predictive accuracy of MUAC as an alternate measure against BMI to determine both undernutrition and overweight-obesity. Further, the validations are necessary to check the suitability of the proposed MUAC cut-offs for health outcomes and community-specific nutritional status among vulnerable segments.