According to Seder Olam Zuta, Jehoshaphat was a High Priest of Israel, succeeding Jehoiarib

Jehoiarib

Jehoiarib was the head of a family of priests, which was made the first of the twenty-four priestly divisions organized by King David.- High Priest :...

 and succeeded by Jehoiada

Jehoiada

Jehoiada in the Hebrew Bible, was a prominent priest during the reigns of Ahaziah, Athaliah, and Joash. By his arranged marriage with the princess Jehosheba , he became the brother-in-law of King Ahaziah...

. According to Josephus

Josephus

Titus Flavius Josephus , also called Joseph ben Matityahu , was a 1st-century Romano-Jewish historian and hagiographer of priestly and royal ancestry who recorded Jewish history, with special emphasis on the 1st century AD and the First Jewish–Roman War, which resulted in the Destruction of...

, the second High Priest after Joram

Joash (high priest)

Joash was the fourth High Priest of Solomon's Temple. Josephus wrote that after Azariah his son 'Joram' became the new High Priest. The third name in the High Priest family line of is 'Johanan'....

 (chronological place of Jehoshaphat) was Pediah

Pediah

Pediah was the High Priest of Solomon's Temple. Josephus wrote that after Axioramos his son 'Phideas' became the new High Priest. Pediah doesn't appear in the High Priest family line of , at his chronological position the name 'Ahitub' appears....

. Josephus does not mention a Jehoshaphat. Jehoshaphat is also never mentioned in the Tanakh

Tanakh

The Tanakh is a name used in Judaism for the canon of the Hebrew Bible. The Tanakh is also known as the Masoretic Text or the Miqra. The name is an acronym formed from the initial Hebrew letters of the Masoretic Text's three traditional subdivisions: The Torah , Nevi'im and Ketuvim —hence...

, his name doesn't appear in the list of the Zadokite dynasty .