Groundnut Rosette Disease (GRD) is one of the most severe biotic constraints limiting groundnut (Arachis hypogaea L.) production in sub-Saharan Africa, often causing devastating yield losses in smallholder farming systems. This study evaluated the resistance to GRD and grain yield performance of 20 advanced groundnut lines across 11 diverse environments in northern Mozambique over four growing seasons (2014–2018). Trials were conducted using an alpha-lattice design with two replications per location, each comprising four incomplete blocks. Traits assessed included phenological development (days to emergence, flowering, and harvest), plant establishment (number of emerged and harvested plants), yield components (pods per square meter, maturity percentage, 100-seed weight, grain percentage, pod yield, grain yield), and GRD incidence. Data were subjected to combined analysis of variance, genotype-by-environment (G×E) interaction assessment, stability analysis, AMMI and SREG biplot models, and principal component analysis. Significant G×E effects were observed, indicating that environmental factors played a dominant role in trait expression. GRD incidence was most pronounced in the NPL_15 environment, where the susceptible check JL-24 showed 70% infection. In contrast, advanced lines 7508, 7533, and 7566 consistently exhibited high resistance, with only 2% incidence. Yield performance was not consistently correlated with GRD incidence, but high grain yields were associated with superior plant stand at harvest, pod density, and grain recovery percentage. Line 7510 demonstrated broad adaptation across test sites, whereas lines 96714 and 7539 displayed specific adaptation to Namapa and Mapupulo environments, respectively. These findings highlight promising resistant genotypes for deployment in breeding programs targeting GRD-endemic regions of Mozambique.