Being part of a longer-term package worth £150 million, the new offering will see existing customers on a standard variable tariff pay £50 less than the current price cap.
The energy supplier has also doubled its financial hardship fund, which now stands at £5 million – it is estimated that the scheme has helped more than 36,000 people so far.
Greg Jackson, Founder of Octopus Energy Group, said: “We’ve already absorbed £100 million of the costs on behalf of customers and we’re choosing to absorb another £50 million here by keeping costs for existing flexible tariff customers well below the cap – and much lower than any other large company.
“We’re also doubling our financial assistance fund for those most in need and we’ll do all we can to help customers through this.
“That includes increased investment in staff and systems to maintain the service levels which make us the only provider recommended by Which? and ensures there’s someone to speak to when customers need it.”