This paper, for the first time, proposes a novel stochastic model-based eye-diagram estimation method for 8B/10B and transition-minimized differential signaling (TMDS)-encoded high-speed channels. A stochastic model describes a behavior of an encoder with respect to probability. The previous eye-diagram estimation methods are based on an assumption that each bit has the same probability for 1 s and 0 s. However, the assumption limits to estimate an accurate eye-diagram for encoded high-speed channels. We first propose and apply the stochastic model for two types of 8B/10B encodings: 8B/10B and TMDS. For verification, we design the 8B/10B and TMDS encoder within MATLAB. The transient simulation for the 8B/10B encoded channels requires 9700 and 6600 s, respectively. However, the proposed method only requires 23 s in both cases. Furthermore, in the bit-error rate, the transient simulation provides the bathtub curve up to 10−2 due to processing time and computing resources. In contrast, the proposed method with the stochastic model provides the bathtub curve up to 10−8. In conclusion, this paper successfully proposes and verifies the stochastic model-based eye-diagram estimation method for 8B/10B-encoded high-speed channels.