EnBW's basic supply tariff is set to increase by an average of 31.1%, and other tariffs will see a similar increase, the Stuttgarter Zeitung reported, citing the company.
A spokesman put the number of customers affected in the "lower million range", the newspaper said.
EnBW did not rule out further price hikes as a result of the Ukraine war, which has set Germany on a quest for alternative energy sources.
Inflation in Europe's largest economy edged up in July to 8.5%, and Chancellor Olaf Scholz has promised low-income households more support to foot energy bills. [L8N2Z96VP] [L8N2Z33A3]
In order to stop prices spiralling further, "we must now do everything in our power to ensure that we become completely independent of Russian imports as quickly as possible and massively expand renewable energies," said EnBW board member for sales Colette Rueckert-Hennen.
The development of regenerative energy sources would even have "a cost-reducing effect" in the long term, the Stuttgarter Zeitung quoted her as saying.
(Writing by Rachel More, Editing by Miranda Murray)