Mr Corbyn saw off challenger Owen Smith with 61.8% of more than half a million votes cast in the contest.
His tally of 313,209 votes was more than 60,000 higher than the 251,417 (59.5%) he secured in 2015.
Mr Smith took 193,229 votes - 38.2% of the 506,438 votes cast out of a total electorate of 654,006.
Mr Corbyn thanked voters for their “trust and support” and told defeated challenger Owen Smith they were “part of the same Labour family”. Addressing the bitter divisions that have split his party, Mr Corbyn added: “In our party we have much more in common than that which divides us.”
He added: “Politics is demeaned and corroded by intimidation and abuse. It is not my way and it is not the Labour way.”
Mr Smith congratulated Mr Corbyn on “being elected decisively as our leader”, adding: “Now is time for all of us to work to take Labour back to power.”
The Labour leader called on MPs to unite behind him and help build support for “a genuine alternative” to the Conservative Government.
“I have no doubt this party can win the next general election whenever the Prime Minister calls it, and form that next government,” he said.
“To do that, we have all got to work together.”
Mr Corbyn said he had a responsibility as leader to unite the party at conference, in Parliament and across the country.
But he added: “It is also the responsibility of the whole party - Members of Parliament, councillors, party members and our wonderful supporters across the country - to work together and respect the democratic choice that’s been made.”
Scottish Labour leader Kezia Dugdale, who had previously warned that a Corbyn victory would lead to a generation of Tory rule, called on the Labour leader to unite the party.
“Hundreds of thousands of people across the UK took part in this election and the Labour Party is now the largest party in Europe,” she said.
“We need to harness the energy and enthusiasm of our movement into real change for the people of the UK.
“Jeremy can unite the Labour Party, but he needs to want to unite it. That means he needs to work with both the party across the country and MPs to provide an effective opposition to the Tories in Westminster.
“It will be a difficult task for Jeremy, but not an impossible one. Likewise, the Parliamentary Labour Party must recognise that a divided Labour Party serves no one. We can’t fight the Tories when we are fighting each other.”