UEFA initially announced its plans for the international competition in March as a way of replacing a number of friendly dates.
The Nations League will see 54 teams compete in four divisions based on strength, with countries further divided into groups that will alter based on promotions and relegations.
In each division, four group winners are promoted and the four bottom sides relegated, while the four group winners in the top division will qualify for Euro 2020.
The Nations League will be played from September to November 2018, with UEFA stating the tournament will serve as an ideal replacement for some international friendly dates.
"The key driver of the UEFA Nations League is sporting integrity, as member associations, coaches, players and supporters increasingly feel that friendly internationals are not providing adequate sporting competition," the organisation said in a statement.
"In addition, the competition will help UEFA realise its stated goal of improving the quality and standing of national team football while maintaining the balance between club and international football.
"The competition will establish the UEFA Nations League champions every odd year while also allowing all nations to play competitively at their level."
