It rises at the lake Torneträsk near the border with Norway and flows generally southeast for a distance of 522 kilometres (324 mi) into the Gulf of Bothnia.

The source of the Torne is generally believed to be the lake Torneträsk near the border with Norway.

That river comes from Lake Válfojávri in Norway's Nordland, but near to that lake it is joined by a nameless, longer stream, according to official Swedish maps fed by a small glacier, 1,189 m (3,901 ft) above sea level (68°16′02″N 18°07′41″E / 68.26722°N 18.12806°E / 68.26722; 18.12806).

Other affluents of Lake Torne are Njuoraätno and Kåppasjåkka in the west, Gurttejohka, Snurrijåkka, Bessešjohka, Bággesgorsajohka, Davip Duoptejohka, Lulip Duoptejohka, Sarvájohka and others in the north, and Rákkasjohka, Gohpasjohka, Miellejohka, Bessešjohka, Golkkokjohka, Nivsakkjohka and others in the south.

On the south shore of Torne lake are Björkliden, Abisko, Stordalen, Kaisepakte.

[6] Beyond the lake, the Torne River flows unhindered by any concentrations of human inhabitants until the village of Kurravaara, around 12 kilometres (7 mi) northeast of Kiruna.

The river then proceeds to Kuoksu, where it is crossed by the road to Lainio and Oksajärvi, and to Juopakosku, where the Junojoki joins from the left.

The river continues south to Svanstein, crosses the arctic circle at Juoksengi and proceeds to Niskanpää and Kuivakangas.

Here, the 127-kilometre (79 mi) long Tengeliön River joins from the (Finnish) left side .

At Karungi, the Liakanjoki departs from the Torne river and flows to the Gulf of Bothnia independently in Finland.

Before finally arriving at the twin city of Haparanda/Tornio, it passes by the villages Vojakkala and Mattila.

Near Haparanda/Tornio the border was fixed in the treaty, partly on land, so the city of Tornio would belong to Russia.

The Finnish spoken in informal conversation is similar on both sides of the river, although some newer words differ.