A model of holographic dark energy is proposed, where the infrared cut-off is related to the event horizon. Using ΩΛ = 0.73, the equation of state of dark energy at present is predicted to be w = -0.90. The cosmic coincidence problem is resolved by inflation, assuming a minimal number of e-foldings. The model addresses the cosmological constant problem, with dark energy's equation of state derived from the holographic principle. The dark energy density is related to the event horizon, and the model predicts the dark energy behaves as a cosmological constant when c = 1. The model also predicts the equation of state parameter w at present time, agreeing with observational data. The model suggests that the dark energy density is small enough not to disrupt standard cosmological results. The model also addresses the cosmic coincidence problem by showing that the dark energy density is small compared to radiation density at the onset of the radiation-dominated epoch. The model is viable if dark energy eventually decays, and it is consistent with inflationary theory. The model predicts the dark energy equation of state and is falsifiable by future experiments. The model is supported by the assumption that the infrared cut-off is the event horizon, and it provides a concrete prediction for the dark energy equation of state. The model is consistent with the observed value of ΩΛ and the current value of w. The model is also consistent with the idea that the dark energy density is small compared to radiation density at the onset of the radiation-dominated epoch. The model is viable and provides a concrete prediction for the dark energy equation of state.A model of holographic dark energy is proposed, where the infrared cut-off is related to the event horizon. Using ΩΛ = 0.73, the equation of state of dark energy at present is predicted to be w = -0.90. The cosmic coincidence problem is resolved by inflation, assuming a minimal number of e-foldings. The model addresses the cosmological constant problem, with dark energy's equation of state derived from the holographic principle. The dark energy density is related to the event horizon, and the model predicts the dark energy behaves as a cosmological constant when c = 1. The model also predicts the equation of state parameter w at present time, agreeing with observational data. The model suggests that the dark energy density is small enough not to disrupt standard cosmological results. The model also addresses the cosmic coincidence problem by showing that the dark energy density is small compared to radiation density at the onset of the radiation-dominated epoch. The model is viable if dark energy eventually decays, and it is consistent with inflationary theory. The model predicts the dark energy equation of state and is falsifiable by future experiments. The model is supported by the assumption that the infrared cut-off is the event horizon, and it provides a concrete prediction for the dark energy equation of state. The model is consistent with the observed value of ΩΛ and the current value of w. The model is also consistent with the idea that the dark energy density is small compared to radiation density at the onset of the radiation-dominated epoch. The model is viable and provides a concrete prediction for the dark energy equation of state.