The Latics confirmed late on Tuesday that they had agreed a deal to sign Collison on loan for the rest of the campaign as he heads to the DW Stadium hoping to get some regular first-team action.
Rosler is pleased to have landed an experienced Premier League performer and believes he is just what his side needs for the Championship run-in.
"Jack is exactly what we needed, he can play in a few different positions, has terrific experience of both the Premier League and the Championship and will heighten competition for places as we move into the crucial last few weeks of the season," he said.
The Wales international could make his Latics debut in Saturday's home league fixture against Watford, while he will also hope to feature in Wigan's FA Cup semi-final against Arsenal at Wembley on April 12.
Collison has slipped down the pecking order at Upton Park this season under boss Sam Allardyce, making just 10 Premier League appearances so far.
West Ham last week