By the consistent growth of the city, some smaller villages around – though officially municipalities in their own right – are now widely considered to be suburbs of Lienz.

The area was incorporated into the province of Noricum and Emperor Claudius had a municipium called Aguntum erected near Lienz in the today's municipality of Dölsach.

Aguntum became the see of an Early Christian bishop in the 5th century but decayed during the Slavic settlement of the Eastern Alps and the subsequent fights with the Bavarii under Duke Tassilo I around 600.

It was then purchased by the scions of the Meinhardiner dynasty, who held the office of Aquileian Vögte (reeves) and chose Lienz as a residence.

Located on the important trade route from Venzone in Friuli to Salzburg, the market town of Lienz received city rights on 25 February 1242.

When the Meinhardiner became extinct in 1500 upon the death of Count Leonhard of Gorizia, their estates were bequeathed to the Habsburg King Maximilian I and finally incorporated into the County of Tyrol.

After the Austrian defeat at the Battle of Austerlitz, Lienz with Tyrol passed to the newly elevated Kingdom of Bavaria according to the 1805 Peace of Pressburg.

After the 1938 Anschluss of the Federal State of Austria into Nazi Germany, the Lienz district became a part of Reichsgau Kärnten (Carinthia).