Recent high-precision cosmological observations have revealed statistically significanttensions between early-universe inferences and late-time measurements, most notably in theHubble constant H0 and the clustering amplitude parameter S8. These discrepancies mayindicate limitations of the standard ΛCDM framework when extrapolated across cosmicepochs. In this work, we develop a thermodynamically motivated cosmological model in which the dark energy component is not introduced as a fundamental constant, but instead emerges dynamically from the thermodynamics of the apparent horizon. By applying Hayward’s unified first law in conjunction with the Clausius relation to the cosmological apparent horizon, we derive a self-consistent evolution equation for the Hubble parameter H(z). Numerical integration of the resulting evolution law yields a present-day expansion rate H0 ≃ 71.0 kms−1 Mpc−1, which lies between cosmic microwave background inferences and local distance ladder measurements. The model further predicts a present-day matter density Ωm,0 = 0.2677 and a clustering parameter S8 = 0.781, both of which are consistent withrecent weak lensing constraints. ...notably in the Hubble constant H0 [2] and the clusteringamplitude parameter S8 [8]. These results suggest that horizon thermodynamics may provide a viable mechanism for generating an effective dark energy component, and that the observed cosmological tensions could reflect an incomplete thermodynamic description of the cosmic expansion history rather than the need for new fundamental fields.