His uncle Gontran adopted him in 577, to form an alliance against Chilpéric, but in 581 Chilpéric also adopted Childebert. Gontran ceded lands to Childebert and thus overturned Chilpéric's move. But when Chilpéric died in 584, to be succeeded by his baby son Clotaire II, Gontran attacked his adoptive son, but only succeeded in taking part of his kingdom.
At a peace conference in 587 the leaders settled their differences. In 592 Gontran died, and Childebert II took the throne of Burgundy and immediately made war against his cousin, Clotaire, but was defeated in 593. When Childebert died in 595 his kingdom was divided between his two sons, Théodebert II and Thierry II.