Big Six energy provider SSE has said it will sell its household business to Ovo Group in a £500 million deal.
SSE is the third largest supplier in the UK energy market, with around 3.5 million household customers and 8,000 staff. All will be transferred as part of the deal.
SSE chief executive Alistair Phillips-Davies said: "We have long believed that a dedicated, focused and independent retailer will ultimately best serve customers, employees and other stakeholders - and this is an excellent opportunity to make that happen."
OVO was founded in 2009 and has grown to become the UK's largest independent energy supplier, now serving 1.5 million customers.
Ovo founder Stephen Fitzpatrick said: "SSE and OVO are a great fit. They share our values on sustainability and serving customers. They've built an excellent team that I'm really looking forward to working with."
The move allows SSE to focus on "developing, operating and owning energy and related infrastructure in a sustainable way" rather than a customer-facing business.
“Following the transaction, SSE will be able to give an even greater focus to delivering the low carbon infrastructure needed to help the UK reach net zero emissions," Phillips-Davies said.
The takeover is expected to complete later this year or early next year.