Understanding farmers’ preferences and willingness to pay for different traits is critical for demand-driven varietal development and designing targeted strategies that stimulate adoption of varieties by farmers. This study uses choice experiment data from a random sample of 1299 Tanzanian farmers to analyze their preferences for traits of groundnut varieties, investigate trade-offs involved in valuation of attributes, and explore heterogeneity in preferences. Results reveal that farmers have strong preferences for groundnut varieties that are high yielding, tolerant to environmental stresses, early-maturing, red-colored, and fetching high sale prices in grain markets. Farmers are willing to pay the highest premium for high-yielding attributes, closely followed by the tolerance trait. Further, a latent class analysis identifies four distinct classes of farmers, confirming considerable heterogeneity in farmers’ preferences for various groundnut traits. A specific distinction is notable between preferences of consumption-oriented and market-oriented farmer classes. Our results have important implications for demand-driven variety development and targeted dissemination of improved varieties.