Addressing a hall of 4500 people alongside AfD party leader Alice Weidel, Musk spoke live via video link about preserving German culture and protecting the German people.
"It's good to be proud of German culture, German values, and not to lose that in some sort of multiculturalism that dilutes everything," Musk said.
Despite winter weather, anti-far right campaigners were out in force on Saturday, with around 100,000 gathering around Berlin's Brandenburg gate and up to 20,000 in Cologne, including people of all ages carrying colourful umbrellas.
Some 100,000 people have protested against the far right at Berlin's Brandenburg gate. (EPA PHOTO)
Last week, the US billionaire caused uproar after he made a gesture that drew online comparisons to a Nazi salute during US President Donald Trump's inauguration festivities.
On Saturday, he said: "children should not be guilty of the sins of their parents, let alone their great grandparents," apparently referring to Germany's Nazi past.
"There is too much focus on past guilt, and we need to move beyond that," he said.
Musk, who spoke of suppression of speech under Germany's government, has previously attacked German Chancellor Olaf Scholz on X.
For his part, Scholz on Tuesday said he does not support freedom of speech when it is used for extreme-right views.
Musk spoke in favour of voting for the far right party, saying: "I'm very excited for the AfD, I think you're really the best hope for Germany fight for a great future for Germany".
Weidel thanked him, said the Republicans were making America great again, and called on her supporters to make Germany great again.
Earlier this month, Musk hosted Weidel in an interview on X, stirring concern about election meddling.
