When the IsraŽlites arrived in Canašn around 1200 BC the Jebusites were ruled by a king named Adonizedek (Joshua 10:1,23), who participated in a coalition of kings from Jarmut, Lachish, Eglon and Hebron against IsraŽl. Joshua defeated the coalition and slew Adonizedek.
Despite the death of Adonizedek, the Jebusites remained well established in Jebus itself, although their role in Canaan was significantly reduced.
Jebus was the strongest fortress in Canaan and its defenses were considered inpenetrable. This is the reason why the Jebusites said that they could defeat David's army with the blind and the lame, when David asked the Jebusites to give the city to him as his capital. But David and his men took Jebus by surprise after entering the water tunnel which supplied the city with water.
The last mention of the Jebusites in the Bible is when David purchases from Ornan the Jebusite, also called Araunah (2 Samuel 24:16-25), the threshing-floor on Mount Moriah, a place apparently already consecrated to the grain goddess, in order to build an altar to Yahweh. The transaction is accounted in 1 Chronicles 21:22-25.
It is unknown what became of the Jebusites, but it seems logical that they were assimilated by the IsraŽlites.