Feature weighting is one of the fundamental problems in machine learning algorithms and data mining to determine the importance of features. In this study, a novel feature weighting method using Covariance Matrix Adaptation Evolution Strategy (CMA-ES) optimization method for classification process is proposed. Experimental results are obtained by 10-fold cross validation technique with 3 different classifier models: Naive Bayes (NB), K nearest neighbors (K-NN) and Random Forest (RF) on 5 datasets in UCI Machine Learning Repository. Classification accuracy rate is used as the performance criterion. In addition, the developed CMAES-based method is also adapted to optimize these 3 classifiers in a voting-based ensemble algorithm. In this context, a different ensemble-based method is presented with CMAES-based feature weights obtained when the classifiers are individually and all together. Experimental studies show that the developed method gives better performance and promising results than the results obtained without feature weighting.