Introduction: Predict running performances is very important for athletes and trainers. Sport researchers have therefore developed certain tools to predict running performances, but only in non-obstacle races. This study aimed to develop and test the validity and accuracy of an equation for predicting 3,000-m steeplechase performance (PerfSteeple). Methods: The official rankings of French runners for the 3,000-m track-running (Perf3000) and 3,000-m steeplechase events were examined. Age, height and body mass were collected. From 146 included athletes, two groups were randomly composed: one comprising 80% of the sample (n = 117) to develop a simple equation to predict PerfSteeple (i.e., development group) and the other comprising the remaining 20% (n = 29) to test the validity and accuracy of the developed prediction equation (i.e., cross-validation group). Results: The simple prediction equation included Perf3000 and age: PerfSteeple=−57,165+1,147×Perf3000+0,955×age . No significant difference was noted between the actual and predicted performances. Predicted performances were significantly correlated with the actual ones, with a very high correlation coefficient (p < 0.001; r = 0.929). Bias and 95% limits of agreement were −5 ± 24 s, i.e., −0.8 ± 7.6%. In 95 of 100 new predictions, the difference between actual and predicted performance would be less or equal to—5 ± 24 s. Discussion: The study confirms the validity and accuracy of the equation for predicting PerfSteeple. Predictions using this simple equation may be used in training and competitions for athletes and coaches. PerfSteeple = −57,165 + 1,147 X Perf3000 + 0,955 X age.