The 54-year-old was initially expected to consider his future after the Copa America next year but now looks set to stay until the tournament in Russia.
Sampaoli's men were eliminated from the 2014 tournament on penalties by host Brazil in the last 16, but beat Spain 2-0 in their impressive run to the knockout stage.
The 54-year-old had initially committed to the role until next year's Copa America, but has now said that he is prepared to stay until the next World Cup.
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The Chilean professional football association (ANFP) confirmed the news in a statement Tuesday.
The statement quotes Sampaoli as saying: "After meeting this morning with the president of ANFP and the FFCh (Chilean Football Federation), Mr. Sergio Jadue, I wish to inform that I have taken the decision to remain in the position of technical director of the Chile national team and direct it to the 2015 Copa America in Chile, the Copa America's centenary in 2016 in the United States and the qualifiers for Russia 2018, including our participation in such a World Cup."
Argentinian Sampaoli took charge of the national team in 2012 following a successful stint as coach of Universidad de Chile.