Benn defeated Labour Brexiteer Kate Hoey to win the spot, which will see him lead 20 other MPs from across party's in scrutinising the work of David Davis' department for exiting the European Union.
It marks a return to the spotlight for Benn, who served on Labour's frontbench under Jeremy Corbyn until being dismissed in the aftermath of the EU referendum.
It represented the culmination of bitter tensions between Benn and Corbyn after both publicly took opposing stances on the bombing of Syria, with Benn's speech winning support from across the House of Commons.
Benn's sacking was the first step in a long summer of protest from Labour MPs, with large numbers of shadow cabinet and frontbench representatives resigning before Corbyn triumphed in a leadership contest last month.
Also returning to the fore is Yvette Cooper, who has been elected chair of the home affairs committee, just over a year after she was defeated by Corbyn in the previous leadership battle.
Cooper had served under Ed Miliband as shadow home secretary, and has become a prominent voice in parliament campaigning on the need for greater protection for refugees.
In winning the seat she defeated existing home affairs committee member and Streatham MP Chuka Umunna, public accounts committee member Caroline Flint and Corbyn loyalist Paul Flynn.
The SNP's Angus Brendan MacNeil, who previously chaired the abolished Energy and Climate Change committee, will chair the new international trade select committee having faced no opposition.
While Cooper can sit as chair immediately, both Benn and MacNeil will have to wait to start their work while the full membership of their committees is established.