Peanut (Arachis hypogaea) is an important oil and economic crop widely cultivated worldwide. Increasing the oil yield is a major objective for oilseed crop improvement. Plant LEAFY COTYLEDON1s (LEC1s), FUSCA3s (FUS3s), and WRINKLED1s (WRI1s) are known master regulators of seed development and oil biosynthesis. While previous studies in peanut have primarily focused on two AhLEC1s and one AhWRI1 genes, this study identified a broader set of regulators, including two AhLEC1s, two AhFUS3s, nine AhWRI1s, two AhWRI2s, and four AhWRI3s from the variety HY917. The analyses of phylogenetic trees, gene structures, conserved domains, sequence alignment and identity, and collinearity revealed that they were highly similar to their homologs in other plants. Expression profiling demonstrated that two AhLEC1s, two AhFUS3s, and three AhWRI1s (AhWRI1a/b/c) were specifically expressed in developing seeds, suggesting critical roles in seed development, whereas AhWRI1d, AhWRI1f, and AhWRI1g showed high expression in root nodules, pointing to potential functions in symbiosis and nodulation. Furthermore, co-overexpression of AhLEC1b, AhFUS3b, AhWRI1a, and AhWRI1d in Arabidopsis significantly enhanced seed oil content and thousand-seed weight, but also led to reduced germination rate, plant height, and silique length. The findings allow for the extensive evaluation of AhLEC1s, AhFUS3s, and AhWRIs gene families, establishing a useful foundation for future research into their multiple roles in peanut development.