Having forged a centre-right coalition with the three partners a month after Marjan Šarec resigned as prime minister, Janša won 52 votes in a secret ballot in the 90-member legislature with 31 MPs voting against, six abstaining and one invalid ballot.
After he was sworn in, Janša said the incoming coalition faced important challenges but he expressed the conviction that it would be able to address them with responsible management.
Janša now has 15 days to put to parliament his candidates for ministers. "The first step was made today. I expect that I will be able to bring the list of candidates for the new government to this assembly in a relatively short time."
The SDS will put forward candidates that have experience in government as well as Slovenia's 2008 presidency of the EU since Slovenia will preside the bloc again in 2021, according to him.
In an hour-long address to the National Assembly prior to the vote, Janša acknowledged that the government would not be able to achieve everything it wants to given that it has only two years to serve until the next scheduled election.
Its term would therefore be a "compromise on the solutions which all coalition partners agree on", with emphasis on the things that bring the parties together and measures that do not require significant outlays.
Some of the priorities include cutting red tape and decentralisation, including by basing any newly established institutions outside Ljubljana.
Other measures planned in the coalition agreement will have significant fiscal consequences, including higher pensions and a series of family-friendly measures the government plans to take such as expansion of free kindergarten and a universal child allowance.
One of the key policy priorities is the establishment of a "demographic fund", a pension support fund in which state assets would be pooled to help finance public pensions.
"It is time to establish a fund which would absorb the remaining state assets and manage them with a profit for the benefit of the generation which has created these assets," he said.
The new government plans to liberalise the economy and introduce competition in education and healthcare. As least as a temporary measure to improve national security, it also plans to re-introduce military conscription.
Janša has often been accused of being too radical, in particular due to his anti-immigration sentiment in recent years, but his statements suggest he has softened his stance on migrations.
He said that migrants would be welcome if invited, provided they accepted the fundamental tenets of the "majority culture". "They cannot expect that we will accept their habits, their manner of behaviour, their culture, but we justifiably expect that they will accept ours."
The debate in parliament saw the members of the new coalition pledging to work for the benefit of the entire society and rejecting criticism by the new opposition about the prospects of the new government being too far to the right.
"The experience from recent years makes us justifiably doubt that someone can become wise, tolerant, respectful, just and inclusive over night," said Brane Golubović, the head of the deputy group of the Marjan Šarec List (LMŠ).
The new opposition spent a significant portion of the allotted time arguing about who and what caused the Šarec government to collapse, with the Left, whose termination of a cooperation deal with the minority government was a major milestone, often in the focus of criticism.
Slovenia may have a new government with full powers within three weeks, the third led by Janša after stints in 2004-2008 and in 2012-2013.
The undisputed leader of the Slovenian conservative bloc, Janša is considered the most experienced politician in Slovenia, his career spanning over three decades.
Aside from having served as prime minister twice already, he was defence minister in three governments in 1990-1994, and again in 2000, during the interim Andrej Bajuk government.