20 In the time of Jehoram, Edom rebelled against Judah and set up its own king.

Read 2 Kings 8:20 Using Other Translations

In his days Edom revolted from under the hand of Judah, and made a king over themselves.
In his days Edom revolted from the rule of Judah and set up a king of their own.
During Jehoram’s reign, the Edomites revolted against Judah and crowned their own king.