This allows the country to separate its power system and decouple from Russia.
Belgia-based ENTSO-E represents dozens European transmission system operators. It said that the electricity grids in Ukraine and Moldova were successfully synchronized on a trial basis with the Continental European Power System.
The group stated that "this is a significant milestone."
After Russia's 2014 annexation, grid operators had been planning such a move. However, the massive Russian military attack on Ukraine last month prompted Kyiv to request an urgent speeding up of a process that was likely to take many years longer.
ENTSO-E's 39 members manage the largest interconnected electric grid in the world. This move will allow them to support the stability of the Ukrainian, and Moldovan power systems.
These two countries were once part of the Integrated Power System, which also includes Russia or Belarus. Despite the fact that there had been no electricity trade between them for many years, this made Ukraine dependent upon Russia's grid operator.
"This will allow Ukraine to receive electricity if Russia continues to destroy our power infrastructure and save our power system," stated Volodymyr Kudrytskyi who is the chairman of the management board for Ukrenergo, Ukraine's grid operator. "We are deeply grateful to our European partners"
Georg Zachmann, a Brussels-based expert, stated that the switch will enable energy suppliers in the continent grid stretching from Portugal to Poland to supply electricity for Ukraine if needed.
He said that this could enable Ukraine to shut down some of its coal-fired power stations it keeps running in order to maintain grid stability and save precious fuel during wartime.
Over the long-term, Ukraine could export excess electricity from its nuclear power plants to Europe.
Zachmann said, "It's an excellent win-win situation." It might even be beneficial for the climate.