Modern measuring methods proved that Liechtenstein's borders are 1.9km (1.2 miles) longer than previously thought.
The border has been changed in some of the more remote corners of the mainly mountainous state, which has now grown in size by 0.5sq km (123 acres).
Liechtenstein, population 35,000, now boasts 77.9km (48.3 miles) of borders, an area of 160 sq km (62 sq miles).
The newly-discovered territory is equivalent to about the size of 50 football pitches.
Sixth smallest
Announcing its territorial expansion, the government of Liechtenstein said that some areas of the Alpine nation had never been properly measured until now.
Liechtenstein's royal family kept the principality neutral during both world wars, and then developed a reputation as a tax haven in the decades afterwards.
The current ruler, Prince Hans-Adam II, has a vast personal fortune and is said to be one of the richest heads of state in the world.
Despite its new-found territory, Liechtenstein is the sixth smallest independent state in the world, larger than only the Vatican City, Monaco, San Marino, and the Pacific island nations of Tuvalu and Nauru.
The next largest nation, the Marshall Islands, is some 20sq km bigger than Liechtenstein, and appears in little danger of being overtaken any time soon.