The Scottish Labour leader also hit out at the SNP and claimed they did not represent the values of Scotland.
Speaking at his party’s conference in Brighton on Monday, Mr Sarwar urged his party to offer a more positive vision of what the UK could be.
He said: “We hear a lot about the red wall. The first red wall to fall was Scotland. And unless we rebuild, there we won’t get a UK Labour Government.
“But to do that we need to present a different, more positive vision of Scotland and Britain. One that is outward looking, diverse and tolerant.
“Because despite what Nicola Sturgeon and the Tories want us to believe, Boris isn’t Britain. Our vaccinators, our NHS staff, our social care staff, our postal workers, our retail workers, our key workers and all who pulled us through this pandemic – they are Britain.
“Don’t allow the SNP and the Tories to define Englishness. England isn’t Jacob Rees-Mogg, Priti Patel and Nigel Farage. England is Marcus Rashford, Gareth Southgate and Emma Raducanu.”
The Glasgow MSP also accused Ms Sturgeon and the SNP of sowing division and grievance, and called for a return to Labour values.
He said: “The values which drive Scotland – hope, opportunity, solidarity. Our values, Labour values.
“The values which drove a Scottish Labour Prime Minister, Gordon Brown, to halve child poverty, not just for children in Scotland, but for children across the United Kingdom.
“And let’s not pretend the SNP and Nicola Sturgeon are our progressive allies.
“And let’s judge the SNP on their record. Attainment gap – widening, child poverty – growing.
“Waiting times – getting longer. And the heart-breaking scandal of the highest drugs death rate in Europe.
“A progressive party would roll up its sleeves. Instead the SNP blame Westminster and carry on campaigning for the only thing that matters to them – independence.”
Pointing towards the COP26 summit in Glasgow in November, Mr Sarwar announced an energy transition commission led by former energy minister Brian Wilson.
He explained: “There is no just transition if it decimates entire communities and sacrifices tens of thousands of jobs.
“We can’t allow a repeat of the end of mining, where communities were hollowed out, workers were stripped of their dignity and our industrial base was destroyed.
“That is the path that the SNP and the Tories currently have us on. The only way to avoid that injustice is to demand a jobs first transition.
“And yes we need to reform the energy sector to meet the challenges ahead, but as energy prices increases we need to take urgent action now.
“In Scotland, 150,000 pensioners live in poverty. The Scottish Parliament has the power to increase winter fuel payments for those pensioners.
“Where the SNP obsess over mandates and white papers, the powers of the Scottish Parliament must be used to end the choice between heating and eating this winter.
“That is why Labour created the Scottish Parliament, that is why power matters and that is what I mean by ‘building the alternative’.”
The SNP have been approached for comment.