ScottishPower has been appointed to take on customers of recently collapsed Entice Energy and Orbit Energy.
It was last Thursday that the two energy firms announced their exit from the market leaving more than 70,000 customers behind.
Money domestic customers of Entice Energy and Orbit Energy have paid into their accounts will be protected, Ofgem said.
The customers are expected to be contacted soon by their new supplier.
Andrew Ward, ScottishPower Chief Executive Officer of UK Retail, said: “The past few months have been unprecedented and have caused a lot of customers great concern about their energy supply.
“We want to reassure our customers, current and new, that their energy supply is safe with us. We are a reliable, stable, integrated energy company with decades of experience generating 100% green energy and delivering net zero.
“We are committed to protecting our customers and providing them with a safe and sustainable energy service. The recent collapse of a number of suppliers shows the need for reform in the energy market to ensure suppliers participating in the sector do so in a way that is fair and transparent for customers.”
Last week, Ofgem launched a consultation after ScottishPower raised payment claims regarding the Supplier of Last Resort (SoLR) process.