The (p, ρ, T) behaviour of ethylene glycol was investigated over the temperature range from T = (283.3 to 393.1) K at pressures from p = (4.8 to 100.1) MPa utilizing a high-pressure vibrating-tube densimeter. This work extends the current data situation for the density of ethylene glycol with respect to temperature and pressure ranges. Four mathematical models for the vibrating-tube densimeter were used to calculate density from the measured oscillation period, and the influence of the model on the resulting density was investigated. The combined expanded uncertainty (k = 2) of the experimental densities was estimated to be 1.57 kg·m−3. The new experimental data were regressed to a Schilling-type correlation equation with its exponent parameters being the same as those for propylene glycol that we studied previously; in a second step, the correlation equation was optimized using an “artificial intelligence powered” modeling tool. With this optimization, the number of the parameters was reduced, while the goodness of the fitting was slightly improved. The combined expanded uncertainties (k = 2) of the correlation equations were estimated to be 1.59 kg·m−3 in the investigated (p, T) range. Carefully selected experimental data from literature generally agree with the correlation equations within the uncertainty of the equation.