The Scot won Wimbledon, the US Open and Olympic gold during two years with Lendl from 2012 to 2014.
Murray was then coached by Amelie Mauresmo before turning back to Lendl in 2016, winning his second Wimbledon title, a second Olympic gold and becoming world number one that year.
“I’m thankful to Ivan for his help and guidance over the years,” Murray said.
“We’ve had great success and learned a lot as a team. My focus now is on getting ready for Australia with the team I have in place and getting back to competing.”
Former world number one and eight-time Grand Slam winner Lendl, 57, added: “I wish Andy well. We had a great run and a lot of fun.”
Murray has been recovering from a hip injury, and his last competitive match was a Wimbledon quarter-final defeat by Sam Querrey in July.
He has since slipped to 16th in the world rankings, but earlier this month he played in a charity match against Roger Federer.
After losing 6-3 3-6 10-6, Murray said he “hoped” to return to competition at the Brisbane International in January.
The tournament is held two weeks before the Australian Open, the first Grand Slam of 2018, which gets under way on 15 January. – BBC
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