Rice is staple food for more than half of the world population and relatively new strategic crop to ensure food security in Ethiopia. In Ethiopia, more than 3336 genotypes were imported from different countries and time, but study on their genetic variability and association of traits was limited. This research was conducted with the objective of evaluating and determining the extent of genetic variability and association of traits of 100 lowland rice genotypes in Northwestern Ethiopia. The experiment was laid out using triple lattice design with10×10 in 2021/22 main cropping season. Analysis of variance indicated that there was statistically highly significant differences (P<0.01) among genotypes for all studied quantitative traits which indicating the presence of sufficient variability for selection. The genotypic coefficient of variation, phenotypic coefficient of variation, heritability and genetic advance as percent of mean, were varied from 8.52% to 72.18%, 8.64% to 86.62%, 63.34% to 98.76% and 17.32% to 136.05%, respectively. Grain yield showed positive and highly significant associations with nine traits for both genotypic and phenotypic correlation. In path analysis, harvest index showed high positive direct effect (0.944) on grain yield followed by biomass yield (0.620) implying that selection of these two traits improve grain yield indirectly. The studied lowland rice genotypes were grouped into four distinct clusters based on quantitative traits and four principal components with eigen value greater than one were contributed to 78.99% of the total variation observed in the studied materials. It is better to cross cluster I with IV genotypes to get early maturing and moderate grain yield variety for moisture stress area. And cross cluster III with IV genotypes to get medium matured, high filled spikelet per panicle, optimized harvest index, biomass and grain yield variety for rain fed with irrigation supplemented areas because genotypes in those clusters are genetically divergent and those genotypes are correlated at both genotypic and phenotypic level. Among 28 qualitative traits, 26 were showed polymorphism except culm angle and ligules shape. Therefore, based on breeders’ objective these 26 qualitative traits had better genotypes. For example, we identified and recommend three genotypes for parents of future breeding works to improve leaf senescence. Finally, more than 12 genotypes were identified for parents of hybridization. However, over time and location repetition is required to increase the scope of validation.