The 25 year old midfielder's contract at the DW Stadium expires at the end of the month and after linking himself with Liverpool, the Senegalese international has moved to Sam Allardyce's West Ham.
Given the move from an established Premier League club to a newly promoted side thre are acusations that Diame has not moved for football reasons, a fact disputed by the Senegalese midfielder.
He said: “I’m very happy and very excited to have joined the club and I’m looking forward to the start of the season.”
Diame did not start a match for the Latics in 2012 after the rise in form of James McArthur and the continued dominance of James McCarthy.
He will however look back upon his time with the Latics fondly. “I’ve been very happy during my time with Wigan. It’s been a great club to play for,” he said. “The fans have always been amazing with me. They made my life easy and I won’t forget that.”
The rumours are that West Ham have stumped up £50,000 and a three year deal to capture Diame's signature.