Lance Batchelor, the chief executive of Tesco's mobile and telecoms businesses, is quitting the grocery giant at the end of February.
He will be replaced by Graham Harris, who is the supermarket's commercial director for non-food hardlines. Mr Batchelor, who joined Tesco in 2007 as marketing director, has taken a role at an unnamed firm.
Meanwhile, Tesco Mobile, which is a joint venture between the grocer and O2, said its customer base grew to more than 2.5 million on Christmas day. It said tens of thousands of Tesco Mobile handsets were activated on 25 December, with the iPhone being the best-seller.