Iakhdunlim was king of Mari in Upper Mesopotamia during the 19th century BC. Of Amorite origin, he became king after the death of his father Iagitlim. Iakhdunlim built Mari up to become one of the major powers of the region. He led a successful campaign to the coast of the Mediterranean. His kingdom was threatned by incursions from various nomad tribes, such as the Canaanites, but he was able to subjugate them and force them to pay tribute. After having established internal peace, he built a temple to the god Shamash.

Elsewhere, Shamshi-Adad I had made himself King of Assyria, and Iakhdunlim received pleads for help from kings threatened by Shamshi-Adad's expansionist plans. But before Iakhdunlim could move against Shamshi-Adad, he was assassinated by his own servants. In the chaos that followed, Shamshi-Adad occupied Mari. Zimrilim, Iakhdunlim's son and heir, was forced to flee to Aleppo, where he would remain as an exile until Shamshi-Adad's death.