This book constitutes the refereed proceedings of the 16th International Conference on Optimization and Applications, OPTIMA 2025, held in Petrovac, Montenegro, during September 22-26, 2025.The 18 full papers included in this book were carefully reviewed and selected from 45 submissions. They were organized in topical sections as follows: ​Mathematical programming; optimal control; optimization and data analysis; applications; discrete and combinatorial optimization; and optimization in economics and finance.