The newly created Dixons Carphone business began trading on the London Stock Exchange.
It features 3,000 stores from the businesses of Dixons Retail Group and Carphone Warehouse.
Dixons Carphone has opened seven shop-in-shops, including one on London’s Oxford Street. Further, 23 stores are slated to open in time for Christmas.
Dixons Carphone chief executive Sebastian James said: "Today is a big day. Our shares officially start trading on the Stock Exchange and we are off to a flying start with the opening of our first combined shops."
Dixons Carphone, which has a market capitalisation of £3.8bn, aims to tap into the way technology will transform households by fusing the mobile phone and electrical goods sectors.
James said: "We’re creating an organisation for the future where the products are just the beginning.
"We will not only help customers to access the technology and the connectivity that is right for them, but also find the expertise and services that bring them to life – the first and best company to offer this complete end-to-end proposition."
Carphone Warehouse is an independent mobile phone retailer, with over 1,700 stores across Europe.