Tamarindus indica L. is a multipurpose monotypic agroforestry species, possessing numerous domestic and industrial applications. It grows naturally in subtropical and semi-arid tropical regions of the world. Sixteen quantitative traits of T. indica were used in this study to unravel the phenotypic diversity on a large scale (422 accessions sourced from 12 districts of 8 Indian states) using multivariate analysis. Significant difference between the provenances were recorded for all the traits (P < 0.001). In terms of total pod weight, shell weight, fiber weight, pulp weight, real pulp value, and seed weight, Karnataka outperformed the other states. There were strong positive associations between real value of pulp (RVP) and all pod size traits ranging from 0.37 to 0.93. Titratable acidity was found to have a significant positive relationship with pod size and pulp recovery (r = 0.513-0.742); sugar/acid ratio with seed percent (r = 0.718) and shell percent (r = 0.537). According to the principal component analysis (PCA), the first five principal components accumulated 98.61% of the variation. Morphological cluster analysis revealed four distinct clusters with high diversity. A unique accession from Karnataka was selected by participatory breeding, enabling the farmer to establish a successful nursery and conserve the valuable genotype. Our study provides valuable information about phenotypic diversity, in situ evaluation, selection indices for plus trees and conservation of tamarind genetic resources in India.