West Ham have signed Ipswich Town defender Aaron Cresswell on a five-year deal for an undisclosed fee.
BBC Radio Suffolk reports that the fee for the 24-year-old will be in excess of £2m, while Tranmere are due to receive 20% from a sell-on clause.
West Brom and Fulham had also shown an interest in the left-back.
Cresswell, who played 42 Championship games last season, could face his former side as early as 16 July, when Ipswich host the Hammers in a friendly.
He has become a mainstay of the Ipswich side since joining from Tranmere in July 2011, failing to start just eight games and being an ever-present in the 2012-13 campaign.
Cresswell completed a medical at West Ham on Thursday.