The 47-year-old had said in August 2016, when extending his contract until 2019, that he would be unlikely to continue beyond that point.
And he has now told Fox Sports: “That will be it. It will be a case of too much time, too much travel.”
Lehmann played 27 Tests and 117 one-day internationals for Australia, taking over as national coach in 2013.
Australia will be in the UK for almost the entire summer of 2019. They will play a one-day international series before England host the World Cup, which is set to run until mid-July, before Australia attempt to defend the Ashes urn and win a Test series on English soil for the first time since 2001.
Lehmann replaced Mickey Arthur as coach shortly before the 2013 Ashes, but despite losing that series 3-0, the Aussies romped to a 5-0 success down under in 2013-14.
England regained the urn with a 3-2 home win in 2015, but Australia already hold an unassailable 3-0 lead in the current series.
Lehmann also led Australia to victory in the 2015 World Cup, beating their co-hosts New Zealand in the final, while another notable series win under his command was a 2-1 Test success in South Africa in 2014.
“For me, I’ve really enjoyed the role and [am] loving it. We’ll just get to that point and work out what we do from there,” he added. (Courtesy BBC)