Jehoiarib (Hebr: "God will contend") was the head of a family of priests, which was made the first of the twenty-four priestly divisions organized by King David.(1 Chr. 24:7)
There is no indication in the Tanakh that Jehoiarib was High Priest, his name doesn't appear in the list of the Zadokite dynasty (1 Chr. 5:30-40, 6:4-15 in other translations).
According to Seder Olam Zuta, he was one of the High Priests of Israel. He succeeded Joash and was succeeded by Jehoshaphat (high priest).
Jehoiarib doesn't appear on the High Priest list written by Josephus in his Antiquities of the Jews. On that list Joram is succeeded by Isus.