In the most passionate defence of his leadership since he won a landslide election in July last year, Starmer called for unity, attacking Brexit campaigner Nigel Farage and his Reform party for only being interested in fomenting division.
Under threat from conservative populist Reform and a nascent leftist party under his predecessor Jeremy Corbyn, Starmer called on voters to be patient with his Labour government, which he said was taking its first steps along the path to "renew Britain".
And he appealed directly to the United Kingdom's working people, saying he understood their frustrations of being "patronised" by politicians, referring to his late father feeling disrespected for having a manual job rather than a university education - something he pledged to change by promoting technical colleges.
"No matter how many people tell me it can't be done, I believe Britain can come together," he told his party's second annual conference in the northern English city of Liverpool since winning power last year.
"We can all see our country faces a choice, a defining choice. Britain stands at a fork in the road. We can choose decency, or we can choose division. Renewal or decline," he said in a challenge to increasingly restive MPs who question his leadership after falling behind Reform in the polls.
In a nod to the difficulties he has faced in the first year as prime minister, with his personal poll ratings the worst for a UK leader since at least 1977, Starmer again committed to raising living standards and putting money in voters' pockets.
But he also sought to convince them that Labour is the true patriotic party rather than Reform, with officials handing out UK flags to the audience, who waved them during several standing ovations.
"For me, patriotism is about love and pride, about serving an interest that is more than yourself, a common good," he said.
"And the question I ask seriously of Nigel Farage and Reform is, do they love our country ... or do they just want to stir the pot of division, because that's worked in their interests?"
He repeated that his government would tackle the high rates of illegal immigration into the UK but would fight racism and those who "say or imply the people cannot be English or British because of the colour of their skin".
That focus on fighting Farage was welcomed by many in the packed conference hall.
"Farage doesn't care about normal people, and it was important we get that message out," said Shabaan Saleem, a 21-year-old Labour councillor.
But Farage said the accusations of racism had put its supporters in danger.
"To accuse countless millions of being racist is a very, very low blow," he said.
"It directly threatens the safety of our elected officials and our campaigners."
