In a statement, Cameron called NATO, to which the United Kingdom has belonged for 40 years, "the cornerstone of our national security."
The meeting would be an opportunity for NATO's 28 member nations to "recognize the contribution and the sacrifice made by our service men and women" as the organization's mission in Afghanistan comes to a close, he said.
Cameron said the summit "will be critical in ensuring NATO remains a relevant, adaptable force fit for the 21st century."
NATO Secretary-General Anders Fogh Rasmussen said in a statement he expected the summit "to deliver an alliance "which is strong, flexible, modern and ready to deal with any security threat."
The last summit was hosted by the United States in Chicago in 2012, the White House noted in a statement, which added "for more than 60 years, NATO has proven itself as the most successful alliance in history."