"Last night I made the decision to end my tenure as head coach of the Dutch national team," Koeman posted on Instagram a day after his nation were beaten on penalties by Morocco.
Koeman received a huge amount of criticism after the defeat, with his decision to switch from a 4-3-3 system that had earned the nation two wins and a draw in the group stage to a 5-2-3 system for the knockout clash leading to the Dutch being dominated by their opponents.
After conceding a stoppage-time equaliser, they saw next to none of the ball in extra time and were fortunate not to concede before ultimately losing on penalties.
The manager stood by his decision after the match, saying he would take the same approach again, but refused to say whether he wished to extend his contract, which expired at the end of the tournament.
"... It hurts that my period at Oranje ends like that," he said in his post. "We all dreamed of a World Cup in which we would write history. That didn't work out."
"No one is more disappointed about that than me. As a head coach, you carry that responsibility. I have always felt that and I will always continue to feel that."
Seemingly confirming his retirement, he mentioned every club that he's coached in his career, and paid tribute to his wife, who is battling illness.
"My wife Bartina has supported and encouraged me every day to finish my work as a national coach, despite her own illness process. That is a testimony to incredible strength. I appreciate her more than I’ll ever be able to put into words."
Those expected to be in contention to replace Koeman include Arne Slot, Erik ten Hag, Peter Bosz and Pep Guardiola.