The Alternative for Germany party has pledged to use its platform in parliament to "reclaim the country and its people." The AfD won nearly 14 percent of the vote in Sunday's election, giving them 94 seats.
Many believed the turmoil of the 20th century had immunized Germany from a return of far-right politics, but Sunday's result proved them wrong.
For the group's opponents who gathered to protest the result in Berlin, the Alternative for Germany's anti-migrant agenda has parallels with the Nazis' rise to power.
"It is the first time since after the war that a racist and neo-Nazi party is in parliament," said one protester. "So that is really worrying to us. And this reminds everyone of 1933."
Jewish groups were among those expressing fear over the results.
The AfD's co-leader, Alexander Gauland, has previously said Germans should be proud of their military's achievements in World War II. However, at a news conference Monday, he denied the party is racist.
Gauland said there is nothing in the party or in its program that could or should disturb Jewish people in Germany. He said his pledge to "reclaim the country" is meant symbolically, adding he does "not want to lose Germany to an invasion of foreign people from foreign cultures."
Analyst Professor Tanja Borzel of Berlin's Free University says Chancellor Angela Merkel's decision to let close to a million migrants into Germany at the height of the migrant and refugee crisis in 2015 led many to punish her at the polls.
Merkel's Christian Democrats won the highest number of votes Sunday, but gained their lowest share in 70 years.
"Most people who voted for the Alternative for Germany did not vote for the party because they share the platform. It was a protest vote, clearly," Borzel said.
The far-right's success overshadowed Merkel's win, which gives her a fourth term in power.
She told supporters Monday that her aspiration is to win the AfD voters back through good politics and problem solving.
Her first problem is forming a government. The second-placed Social Democrats have ruled out working together, so Merkel's best option is likely a coalition with the Liberals and the Greens that could take months, Borzel says.
"It will be very hard to find a compromise on issues such as migration and refugees, but also climate change," Borzel said. "So, we are looking at probably some lengthy negotiations."
The AfD, meanwhile, has pledged to use its new platform in parliament to, in its words, "hunt down" Merkel and reclaim the country.