Dr Finkel was appointed to the advisory body in February.
Energy Minister Lily D'Ambrosio said Dr Finkel had made an invaluable contribution to the advisory panel overseeing how the commission would be established.
"He's had personal reasons why he's made a decision to move on to other things but I really do want to thank him for his service," Ms D'Ambrosio told reporters on Friday.
The revival of the State Electricity Commission was a key promise in the lead up to the 2022 state election.
The government said about one-fifth of Victoria's new energy generation will come from the renewables-only by 2035.
The minister rejected reports on Friday energy costs would rise, saying the commission would lead to cheaper energy.
"I can tell you very clearly, that the more renewable energy that you can produce and create, the cheaper prices will be," she said.
The state opposition claimed the project would not fix energy price woes.
"There are billions of dollars to be spent on infrastructure that doesn't currently exist that needs to exist to bring us that renewable future," opposition spokesperson Richard Riordan said.
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