The magazine, read by the wider farming community including suppliers, service providers and advisers, has been campaigning for farmers since 1893.
The Scottish Farmer is thought to be the world's oldest farming publication, and to mark the milestone, the January 5 issue will feature a 24-page commemorative supplement.
It will feature historical data, stories and pictures from the 12 decades.
Alasdair Fletcher, editor, said: "The research for this supplement created much debate among our staff and I am sure it will create even more comment in farm steadings across the country."
The issue has a comprehensive guide to Scotland's agricultural shows and specialist livestock sales for the year ahead.
Darren Bruce, magazine publisher, said: "Through the last decade the printed magazine has become part of a multi-media environment, now backed with a digital e-edition, an informative award winning website, as well as social media communities which interact with our readers and drive audience to both print and web platforms."