Jennie Formby, south-east regional secretary of Unite, was chosen by Labour’s national executive ahead of her only rival for the job – Christine Blower, former leader of the National Union of Teachers.
The job became vacant after the resignation last month of Iain McNicol, who said he was standing down to pursue new challenges after serving for a “tumultuous seven years”.
Ms Formby has been a Labour Party member for 40 years and has served on the national executive for the past seven years.
She said: “I am honoured to be appointed Labour’s new general secretary. I would like to thank my predecessor, Iain McNicol, for his tireless dedication to the party over the past seven years.
“Last year’s general election showed the strength of our movement when we are united, challenging this Government’s failed and damaging policies and campaigning for real change, in the interests of communities across the UK.
“Labour is preparing for government and I look forward to working with Jeremy Corbyn, our party’s staff, Members of Parliament, members and affiliates to oppose the Conservatives’ destructive austerity programme inside and outside Parliament, and to win elections to build a society that works for the many, not the few.”
Mr McNicol said: “After seven years serving as general secretary and with the party now financially sound I am pleased to be handing over the reins to someone with such strong trade union experience. I’m confident Jennie will build on our electoral gains last year, working with our talented and experienced staff to win the next general election, whenever it comes.
“As someone who has dedicated her life to fighting for workers’ rights, equality and social justice, I know Jennie will put all the commitment, drive and organising talent into getting Labour into government and Jeremy into Number 10.”
Labour leader Jeremy Corbyn said: “I would like to congratulate Jennie Formby on her new role as general secretary of our party. Her talent, experience and commitment to the Labour and Trade Union movement makes me confident she will play a crucial role in building on last year’s inspiring general election advance and taking our party forward to victory.
“The Labour Party is on the cusp of power and we are ready for a general election whenever it comes. We have the team, the passion and the policies to win the support of the British people, form a government and transform our society for the many, not the few.”
Ms Formby worked her way through the union ranks after joining the Transport and General Workers Union (TGWU) in her first job at William Hill in Salisbury after leaving school.
She became a TGWU officer and later held national posts when the union merged to become Unite, including political director.
When she applied for the post of Labour’s general secretary, Ms Formby said the party was more united than for years, under the leadership of Jeremy Corbyn.
She stressed Labour’s links with unions, as well as a growing individual membership far bigger than any other British political party.
Ms Formby is the first female general secretary of the Labour Party in a generation, following Margaret McDonagh, who served from 1998 to 2001.