
Ms Winterton has been shadow leader of the House since May
Rosie Winterton is Labour's new chief whip, after leader Ed Miliband asked the incumbent Nick Brown to step aside.
Ms Winterton was the only MP to enter the ballot to become chief whip - responsible for party discipline.
Jim Fitzpatrick, had said he intended to stand but did not enter, after Mr Miliband asked Ms Winterton to stand.
Labour's chief whip is elected separately to the rest of the shadow cabinet and serves a full parliament.
Mr Brown's decision on Wednesday not to stand - effectively resigning from the post - was seen as a sign of new leader Ed Miliband exerting his authority over the party.
Earlier in the month MPs had voted to allow the chief whip's post to be elected to serve a full term - and Mr Brown, seen as close to former PM Gordon Brown, had intended to stand.
But in letters between him and the party leader, he said Mr Miliband had "indicated" he did not want him to stand for the role again - and as the chief whip should have the "full confidence of the party leader", he would not do so.
Doncaster Central MP Ms Winterton was a minister in the previous government and previously an adviser to John Prescott. She has been shadow leader of the Commons since Labour's election defeat in May.
- Published29 September 2010