Salmonella enterica is a major causative agent of gastroenteritis in humans, with S. Enteritidis and S. Typhimurium amongst the most common serovars. Over recent decades, S. Enteritidis has become a leading cause of invasive non-Typhoidal Salmonella (iNTS) disease, particularly in children and immunocompromised individuals across sub-Saharan Africa. The major public health challenge in low-resource settings and high case fatality-rate of 14.5% underscores the urgent need for comprehensive studies on iNTS. Despite being responsible for approximately one-third of all iNTS cases, S. Enteritidis remains relatively understudied compared to other serovars. Our research focuses on iNTS-associated S. Enteritidis strains from the West African clade (WAC) and Central/Eastern African clade (CEAC). Strains from both clades strains cause a high burden of disease across the region, but the genetic determinants of the invasive phenotype remain to be defined. Using a random barcode transposon site sequencing (RB-TnSeq) approach, we are functionally profiling the genomes of iNTS-associated S. Enteritidis isolates to identify genes important for survival and fitness under conditions relevant to infection. Through a combination of in vitro assays and human macrophage infection experiments, we have identified many expected fitness contributions from core metabolic and stress-response pathways, alongside distinct clade-specific hits. Of particular interest, several prophage-encoded and horizontally acquired genes have emerged as potential contributors to intracellular survival and adaptation. These findings offer new insights into the functional diversity of S. Enteritidis and may inform future strategies for intervention and control of iNTS disease.