Hilary Benn and Yvette Cooper have been elected to chair the Brexit and Home Affairs select committees respectively.
The decision hands a platform to two Labour heavyweight critics of the party leader, Jeremy Corbyn.
Benn, a high-profile Remain campaigner, saw off a prominent Leave supporter, Kate Hoey, and won with 330 votes.
He is the son of Corbyn’s mentor, Tony Benn, but notably disagreed with the Labour leader on the decision to back Syrian airstrikes. Corbyn’s decision to sack him as foreign secretary sparked a wave of resignations from the shadow cabinet.
Cooper was shadow home secretary between 2011 and 2015. She ran against Corbyn for leader in 2015, but lost and has since focused her efforts on chairing Labour’s refugee taskforce.
She saw off two other former front benchers, Chuka Umunna and Caroline Flint to win with 281 votes in the third round.
Chairing select committees offer MPs outside the shadow cabinet a senior position from which they can scrutinise government policy. The Brexit select committee has been newly created to mirror the Department for Exiting the European Union, while the Home Affairs chair was left vacant after Keith Vaz resigned because of a sex scandal.