Jeremy Corbyn has begun reshuffling his top team, with Baroness Chakrabarti appointed shadow attorney general and Diane Abbott named shadow home secretary.
Mr Corbyn needs to rebuild his frontbench team after a mass walk-out of shadow cabinet members opposed to his leadership in the aftermath of the EU referendum in June.
In the first move of the reshuffle, Nick Brown was appointed as the party's new chief whip, replacing Rosie Winterton.
In other appointments, Jo Stevens has been chosen as shadow Wales secretary, while Sarah Champion is now shadow women and equalities minister.
Mr Corbyn said: "I am delighted to confirm the appointments of four extremely talented women to our shadow cabinet.
"These appointments mean, for the first time ever, two out of the three traditional 'great offices of state' will be shadowed by women."
Meanwhile, Sky's Beth Rigby reports shadow education secretary Angela Rayner will be staying in her job.
Lady Chakrabarti carried out a controversial investigation into anti-Semitism in the party, and was made a life peer by Mr Corbyn in the wake of her report.
She insisted there was "nothing remotely transactional" about her report when pressed if there were any talks about a peerage before it was finished.
Ms Abbott was previously shadow health secretary, and her new job marks a major promotion for the long-time Corbyn ally.
With Dawn Butler given the shadow minister for black and minority ethnic communities portfolio, Mr Corbyn said: "I am delighted to announce the appointment of Dawn to my shadow cabinet.
"I am very proud that the Labour Party now has five MPs in our shadow cabinet from the BAME community - the highest number ever in any cabinet or shadow cabinet."
Clive Lewis, who only became an MP for the first time last year, has risen quickly - from shadow defence secretary to shadow business secretary, replacing Jon Trickett.
Shadow chancellor John McDonnell and shadow foreign secretary Emily Thornberry are both expected to retain their roles, meaning the four most senior shadow cabinet positions will be held by London MPs.
The role of shadow Brexit secretary has gone to Keir Starmer, another London MP.
But in a bid to stress regional balance, Mr Corbyn said the choice of Jonathan Reynolds as shadow economic secretary to the Treasury meant there were 10 MPs from the north of England in his top team.
Mr Starmer stormed out of the shadow cabinet in June, and his return brings on board one of the major moderate figures in the party.
Many Corbyn loyalists have been "double jobbing" in multiple roles since the mass walk-out, but the appointment of Mr Brown, an ally of former leader Gordon Brown, suggests some MPs who had previously expressed a lack of confidence in Mr Corbyn could be ready to return.
However, a number of anti-Corbyn MPs have insisted they could not serve under him, including Owen Smith.
Mr Smith challenged Mr Corbyn for the leadership but his bid was easily defeated by the Islington North MP, who was re-elected with an increased share of the vote.
A Labour Party spokesperson said: "Jeremy has today spoken to a number of colleagues in the Parliamentary Labour Party and will continue to do so throughout the day.
"He has begun the process of appointing a new front bench team."
Mr Corbyn has so far resisted calls from former shadow cabinet members for the body's membership to be decided by a ballot of MPs.
Former whip Tom Blenkinsop was quick to criticise the reshuffle, accusing Mr Corbyn of rowing back on his promise to unite the party.
The Labour MP tweeted: "Clear Corbyn wants submission not unity. Ignoring wishes of the PLP and just sacking and appointing regardless."