ADELAIDE, Australia—Gold miners recently celebrated the precious metal fetching its highest price ever. They are reinvesting much of that windfall in copper.

From central Mexico to the Australian Outback, gold producers led by Newmont and Barrick Gold are raising bets on copper through deals and other investments that will give them more influence over a commodity vital to the global energy transition. Copper is essential for building electric vehicles, wind turbines and solar-power systems.