With a short product cycle as we see today, fast and accurate modeling methods are becoming crucial for the development of new generation of electronics devices. Furthermore, increased complexity in circuitry and integration compounds design iteration and the associated, high-dimensional sensitivity analysis and performance optimization studies. Therefore, black-box surrogate models replacing the actual circuitry offer an attractive alternative for more efficient design iteration, optimization and even direct Monte Carlo analysis. In this paper, surrogate models built using non-parametric Gaussian Process are presented. A robust framework based on probabilistic programming is used for training Gaussian Process models. Other methods such as Partial Least-Square Regression, Support Vector Regression and Polynomial Chaos are used to compare with the performance of Gaussian Process. Three design applications, a high-speed channel, a millimeter-wave filter, and a low-noise amplifier are used to demonstrate the robustness of the proposed Gaussian Process based surrogate models.