Labour leadership hopeful Lisa Nandy has been appointed shadow foreign secretary in Keir Starmer's new shadow cabinet.
Other appointments include Anneliese Dodds as shadow chancellor and Nick Thomas-Symonds as shadow home secretary.
The 57-year-old defeated Ms Nandy and Rebecca Long-Bailey in a ballot of party members and other supporters.
Angela Rayner was elected deputy leader, replacing Tom Watson, who stood down as an MP before the general election in December. She will become chair of the Labour Party.
Rachel Reeves has been appointed as the shadow chancellor of the Duchy of Lancaster and Jonathan Ashworth stays as shadow health secretary.
Ms Dodds becomes the first female shadow chancellor.
On her appointment, Ms Nandy, who has been MP for Wigan since 2010, thanked Sir Keir for the "opportunity to serve".
She said: "It's a real honour to be tasked with leading Labour's foreign policy response in these difficult times."
Sir Keir's top team will form a new shadow committee, which will be responsible for coordinating Labour's response to the coronavirus pandemic.
Mr Thomas-Symonds said he was "honoured" to be appointed Labour's shadow home secretary.
Honoured to be appointed @UKLabour Shadow Home Secretary. The immediate task is to focus on the #coronaviruscrisis: as @Keir_Starmer said this morning, we will work constructively with the Government, not scoring political points, but also asking the difficult questions needed.— Nick Thomas-Symonds MP (@NickTorfaen) April 5, 2020
And Ms Reeves said she was looking forward to providing "a constructive opposition at this incredibly difficult time for our country".
It is a huge honour to be appointed by @Keir_Starmer to be shadow chancellor of the Duchy of Lancaster, shadowing the Cabinet Office. I look forward to working with Keir and Team @UKLabour as we provide a constructive opposition at this incredibly difficult time for our country.— Rachel Reeves (@RachelReevesMP) April 5, 2020
Nick Brown has been re-appointed chief whip and Angela Smith remains shadow leader of the Lords.
Sir Keir said: "We are living through a national emergency.
"Under my leadership, the Labour Party will always act in the country's interest to save lives and protect livelihoods.
"That will be the number one priority of my shadow cabinet."
He said they would provide a "responsible opposition that supports the government where we believe they are right" and would "challenge them when we believe mistakes are being made".
Barry Gardiner, sacked as shadow international trade secretary, said on Twitter that he wished Sir Keir and his new team well.
Just received a courteous phone call from @Keir_Starmer standing me down from Shadow Cabinet. I wished him and his new team well.— Barry Gardiner (@BarryGardiner) April 5, 2020
I will continue to do all I can to serve the party and ensure a Labour victory at the next General Election.
And Ian Lavery, sacked as Labour chairman, congratulated Sir Keir on his election victory, and said: "Our new leadership team must continue to embrace the popular common sense agenda developed in the last few years."
More announcements on Sir Keir's team are expected on Monday.
Emily Thornberry, former shadow foreign secretary, has not yet been appointed to a role but remains in the shadow Cabinet.
The cast list of any political leader's top team offers an early insight into their grip on their party, and their political instincts.
We know a fair bit about Sir Keir's internal power - he won the leadership easily and the new look of the party's governing body gives him oomph on the inside too.
We know less about precisely where he'll take the party politically.
So what can we read from the appointments so far?
Those most associated with the Corbyn project are gone: John McDonnell had already said he was off. Today we learnt Ian Lavery and Jon Trickett are trundling up to the backbenches too.
There are none of the names still in the Commons from Labour's time in government - who might have some public recognition value but also cart around political baggage.
Instead: the defeated, the promoted and the retained.
Lisa Nandy, beaten by Sir Keir for the top job, is brought to the top table.
Anneliese Dodds is promoted to lead Labour's shadowing of the Treasury - shadow chancellor is one of the most crucial jobs in opposition.
And Jonathan Ashworth is kept on as shadow health secretary. Having done the job for three and a half years, holding onto him in the middle of a pandemic was clearly important to Sir Keir.
There will be further appointments tomorrow, which will be just as revealing.