"Last night, I made the decision to end my tenure as head coach of the Dutch national team," Koeman wrote on Instagram on Tuesday (Wednesday AEST).
"We all dreamed of a World Cup in which we would make history. That didn't happen. No one is more disappointed about that than I am. As head coach, you bear that responsibility."
Koeman had initially refused to make any definite statement on his future in the aftermath of Monday's penalty shootout defeat in Monterrey, but an underwhelming second stint in charge meant it was always likely he would leave amid a barrage of criticism from Dutch media.
He also hinted at retirement from coaching: "Moreover, the past few years have made me realise once again that there are more important things than football. Football has been my life, but health is priceless. When someone you love dearly is fighting a tough battle, your perspective changes.
"Despite her own illness, my wife Bartina supported and encouraged me every day to finish my work as head coach. That shows incredible strength. I am more grateful to her for that than I could ever put into words," he wrote.
Nigel de Jong, the Dutch football association's technical director, described the World Cup campaign as disappointing. He would have had a major say in whether Koeman stayed or not had the coach not quit.
"The objective was the semi-finals, and the ambition was to become world champions," said De Jong.
"Unfortunately, we didn't achieve that. Yes, we are a long way off. That is the conclusion. We have to be honest about that."
Koeman took over as coach after the last World Cup in Qatar four years ago, under Louis van Gaal, where the Netherlands had made the quarter-finals. The Dutch reached the semis of the 2024 European Championship, but failed to beat a single country ranked in FIFA's top 25.
The 63-year-old previously coached the Netherlands from February 2018 before leaving abruptly in August 2020 to take over at Barcelona.
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