The lager brand, which is estimated to have invested over 拢20m in Scottish football, will debut its sponsorship at the France v Scotland game at Hampden Park on October 7.
The deal also extends to the Scotland B and Scotland women's senior squad, but the brand said it had taken the "positive decision" not to sponsor Scottish any sides under the age of 21.
Tennent's, which has been involved with Scottish football for the last 32 years, said it intended to continue its involvement with the future development of the Scottish game despite ending its Scottish Cup sponsorship.
George Kyle, head of sponsorship at Tennent's Lager, said: "We have taken the decision to announce our withdrawal now to allow the SFA as much time as possible to put a new sponsor in place."
David Taylor, chief executive of the Scottish Football Association, said: "Tennent's have been a long standing supporter of, and investor in, Scottish football.
"The Scottish FA welcomes its continued investment in the game in Scotland with Tennent's sponsorship of the national sides."
A sponsor for the 2008 Scottish Cup has yet to be announced.
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