This study investigates the exciton binding energy and excited states in monolayer tungsten diselenide (WSe₂) using combined linear absorption and two-photon photoluminescence excitation spectroscopy. The exciton binding energy is determined to be 0.37 eV, significantly larger than that in III-V semiconductor quantum wells, making the excited states observable even at room temperature. The exciton excitation spectrum, distinct from the simple two-dimensional (2D) hydrogenic model, reveals reduced and nonlocal dielectric screening of Coulomb interactions in 2D semiconductors. This large exciton binding energy has significant implications for next-generation photonics and optoelectronics applications based on 2D atomic crystals. The experimentally determined exciton states and binding energy provide new insights into the behavior of excitons in 2D semiconductors, highlighting the importance of Coulomb interactions and excitonic effects.This study investigates the exciton binding energy and excited states in monolayer tungsten diselenide (WSe₂) using combined linear absorption and two-photon photoluminescence excitation spectroscopy. The exciton binding energy is determined to be 0.37 eV, significantly larger than that in III-V semiconductor quantum wells, making the excited states observable even at room temperature. The exciton excitation spectrum, distinct from the simple two-dimensional (2D) hydrogenic model, reveals reduced and nonlocal dielectric screening of Coulomb interactions in 2D semiconductors. This large exciton binding energy has significant implications for next-generation photonics and optoelectronics applications based on 2D atomic crystals. The experimentally determined exciton states and binding energy provide new insights into the behavior of excitons in 2D semiconductors, highlighting the importance of Coulomb interactions and excitonic effects.