Moreno has signed a contract through to the end of the 2021-22 season and will start his new job next week. He coached Spain for six games, helping the team qualify for next year’s European Championship.
Jardim’s first spell in charge was from 2014-18, during which time Monaco won the French league in 2017 and reached the Champions League semifinals in the same season.
He returned as coach in January as a replacement for Thierry Henry.
Monaco is seventh in the league, 17 points behind leader Paris Saint-Germain.