"We need to put Sweden's best interests before tactics and prestige," he said in his speech, referring to the "difficult situation in parliament", where there are eight parties and the government holds only 38 per cent of the seats.
He began his speech by talking of the challenges they are facing.
"A new government consisting of the Social Democrats and the Green party is today prepared to shoulder the task. Sweden is in a serious situation. Now we need unity and a joint responsibility," he said.
Löfven said that Sweden shall be a source of inspiration and a role model for the world when it comes to gender equality and climate. "It is possible to change the future," said Löfven, adding that it is possible to strengthen the country's competitiveness. The new government will invest in infrastructure, and at least 250,000 new homes will be built until 2020, he said.
He also said that the business sector will be boosted by cutting its share of the sick pay for employees, by cutting red tape and by investments that encourage exports.
In schools, the teachers will be given more time to do their work and the primary school classes will be smaller, he said.
"The teachers' competencies will be improved and the administrative part of their job will be smaller," said Löfven.
On climate, Löfven said Sweden is currently not meeting 14 out of 16 targets. "The time for failures and apologies is long gone. Climate change is a global security threat. There is time to take responsibility," he said, calling it "one of our generations' biggest challenges".
As for energy, the government's long-term aim is to replace nuclear power with renewable energies. Sweden is aiming for 100 percent renewable energy, Löfven said.
One of the big questions in the election campaign, gender equality, will be getting more emphasis in this government, and the rape laws will be reviewed, said Löfven.
Regarding the contentious issue of profits in the welfare sector, Löfven said there won't be any ban, but "national rules regarding quality". For example, private alternatives shall not be allowed to make profits by cutting the number of staff. All bodies in the publicly financed welfare sector, including private companies, will have to open their books to public inspection.
The previous free-school agreement with the centre right alliance parties will stay in place, but local councils will be given influence over the establishment of new schools in the area, he said.
"Education is not supposed to be a market, but a democratic foundation," said Löfven.
The difference in tax between pensioners and those who are working will be abolished over time. "That pensions are taxed harder than salaries is not reasonable," said Löfven, referring to the fact that the centre-right government has lowered taxes for people who have got a job more than for pensioners and people on benefits.
Löfven also promised free entry to all state museums.
A substantial part of his speech was about the work against racism and prejudice. His government will however abolish the post of Minister for Integration, as "this is an issue for everybody". His government will work for a broad agreement on migration policies, and against recruitment into racist organisations. A national centre against racism will be established. More money will go to SFI, which teaches Swedish to immigrants, and there will be more possibilities for newly arrived immigrants to complement already existing education so that they will get quicker onto the Swedish labour market.
In foreign policy, Sweden will recognise Palestine, said Löfven, adding, "The conflict between Israel and Palestine can only be solved by a two-state-solution."
Löfven also condemned Russia's annexation of Crimea and destabilising influence on Ukraine. Sweden will not apply for membership in Nato: "our policy of military non-alignment continues to serve our country well".