Thunnus alalunga (albacore tuna) is a highly migratory pelagic species of major commercial importance in temperate and tropical oceans worldwide. As an ecologically and economically significant component of pelagic ecosystems and global tuna fisheries, genomic resources are essential to improve understanding of its genetic diversity, population structure, physiological adaptations, and responses to environmental variability. To support these research efforts, a whole-genome assembly was generated for Thunnus alalunga. Genomic DNA was extracted from a blood sample collected in February 2021 in La Réunion, southwestern Indian Ocean. High-molecular-weight DNA was sequenced in February 2022 using PacBio HiFi long-read sequencing technology, and chromosome-scale scaffolding was achieved using Hi-C data. De novo genome assembly was performed with Hifiasm (version 0.16.1) using HiFi and Hi-C reads. Genome annotation was supported by transcriptomic data derived from liver and kidney tissues. Genome completeness and annotation support were evaluated using BUSCO (version 5.7) in protein mode with the Actinopterygii lineage dataset. This resource provides a genomic reference to support research in population genomics, fisheries biology, and conservation of albacore tuna.