Pancreatic cancer is one of the most lethal tumors due to its rapid proliferation and aggressiveness. RAD51AP1 is a protein-coding gene with critical functions in many cancers but few studies have assessed RAD51AP1 in pancreatic cancer. Bioinformatics methods and cell function experiments were performed to reveal the functions of RAD51AP1 in vitro. Gene Expression Profiling Interactive Analysis (GEPIA) was used to explore key proteins and their relationships with RAD51AP1 in the PI3K/AKT/NF-κB signaling pathways. Western blotting (WB) was conducted to detect the expression of key proteins after the downregulation of RAD51AP1. Co-Immunoprecipitation (Co-IP) was applied to confirm the binding of RAD51AP1 and PI3K. In addition, the lentivirus was used to construct subcutaneous tumors in nude mice to verify the function of RAD51AP1 in vivo. The Kaplan-Meier curves illustrated that elevated expression levels of RAD51AP1 were significantly correlated with reduced overall survival (OS), disease-specific survival (DSS), and progression-free interval (PFI) in pancreatic cancer patients. The results of WB showed that several key proteins in the PI3K/AKT/NF-κB signaling pathway (including PI3K, AKT, IKK1, IKK2, P65, P50, C-FLIP, and XIAP) exhibited a significant knockdown upon reducing the expression of RAD51AP1. Co-IP suggested that RAD51AP1 could directly bind to PI3K. In vitro, CCK-8, wound healing, and Transwell assays revealed that high RAD51AP1 expression was significantly correlated with increased cell proliferation, migration, and invasion. In vivo, mouse tumor formation experiments showed that RAD51AP1 inhibition significantly inhibited tumor growth. RAD51AP1 plays an important role in fostering cellular proliferation, invasion, metastasis, and tumor enlargement via the PI3K/AKT/NF-κB signaling pathway.