Jeremy Corbyn announced her appointment as Shadow Secretary of State on Wednesday, along with that of former leadership rival Owen Smith, who will return to the frontbench to take over the Northern Ireland brief.
The Labour leader brought back the man who tried to oust him in 2016 as he began putting together a "strengthened shadow cabinet" following the General Election.
Corbyn's speech was one of many in the first meeting at the House of Commons since the election.
The newly-elected Labour MP in Gordon Brown's former seat has been appointed Shadow Scottish Secretary.
The Pontypridd MP was a special adviser to Northern Ireland secretary Paul Murphy during Tony Blair's government, meaning he already has some knowledge of the job.
Dawn Butler will be shadow minister for diverse communities, while Ian Lavery becomes party chairman.
"We will continue to take the fight to the Tories and I will be out campaigning around the country in Conservative marginals in those extra seats we need to gain to deliver the government for the many that nearly 13 million people voted for last week".
"I was surprised that Jeremy Corbyn added two percentage points, or got two percentage points, more than I had expected and I did say that I would eat this book", Mr Goodwin said while holding up a copy of his Brexit: Why Britain voted to leave the European Union.
Mr Corbyn said on Tuesday that his party should be in "permanent campaign mode" in light of Theresa May's attempts to form a minority government with the backing of the Democratic Unionists.
Gwynne has also been appointed as shadow communities secretary.