Nontrivial topology in type-II Dirac semimetal ${\mathrm{NiTe}}_2$ leading to topologically protected surface states gives rise to fascinating phenomena holding great promise for next-generation electronic and spintronic devices. Key parameters such as lattice parameter, disorder, vacancies, and electron correlation, significantly influence the electronic structure and, subsequently, the physical properties. To resolve the discrepancy between the theoretical description and experimentally observed topological surface states, we comprehensively investigate the electronic structure of ${\mathrm{NiTe}}_2$ using angle-resolved photoemission spectroscopy and density functional theory. Although the bulk electronic structure is found to be well described within mean-field approaches, an accurate description of topological surface states is obtained only by incorporating surface electronic correlation. We reveal that the strongly correlated surface states forming Dirac-like conical crossing much below Fermi level have hybridized $\mathrm{Ni}3d$ and $\mathrm{Te}5p$ character. These findings underscore the intricate interplay between electron correlation and band topology, broadening our understanding of many-body correlation effects on the topological surface states in quantum materials.

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• Electronic structure
• Surface states
• Dirac semimetal
• Topological materials
• van der Waals systems
• Angle-resolved photoemission spectroscopy
• Density functional theory
• Photoemission spectroscopy