The border between the modern states of Switzerland and Italy extends for 744 kilometres (462 mi), from the French-Swiss-Italian tripoint at Mont Dolent in the west to the Austrian-Swiss-Italian tripoint near Piz Lad in the east. Much of the border runs across the High Alps, rising above 4,600 metres (15,100 ft) as it passes east of Dufourspitze, but it also descends to the lowest point in Switzerland as it passes Lago Maggiore at below 200 metres (660 ft).

It is the longest border of both Italy and of Switzerland.

The border is a product of the Napoleonic period, established with the provisional constitution of the Helvetic Republic of 15 January 1798, restored in 1815. While this border existed as a border of Switzerland from 1815, there was only a unified Italian state to allow the existence of a "Swiss-Italian border" with the formation of the Kingdom of Italy in 1861, it previously comprised the borders between Switzerland and the Kingdom of Sardinia, the Kingdom of Lombardy–Venetia and the province of Cisleithania of Austria-Hungary. There remained some territorial disputes after the formation of the Kingdom of Italy, resolved in the Convenzione tra l'Italia e la Svizzera per l'accertamento della frontiera fra la Lombardia ed il Cantone dei Grigioni of 1863.