Martin Schulz, who will challenge German Chancellor Angela Merkel in September national elections, was confirmed leader of the centre-left Social Democrats (SPD) on Sunday by unanimous vote at a party congress in Berlin.
The 61-year-old former European Parliament president became the first leadership candidate to secure 100 per cent of SPD delegates' support since before World War II.
The vote comes amid a buzz of excitement among SPD supporters. Since Schulz was announced as the party's nominee for chancellor, the SPD has climbed to above 30 per cent in opinion polls - after having trailed Merkel's Christian Democrats (CDU) for years at between 20 and 25 per cent.
Schulz told more than 600 party delegates in Berlin that "justice, respect and dignity" will be the cornerstones of the Social Democrat's election campaign manifesto, adding that the SPD governance programme will be presented at a congress in Dortmund at the end of June.
Schulz said he had travelled all over Germany since his return to national politics in January, meeting people "to listen and learn, and to draw necessary conclusions as to what our priorities must be for the coming years."
Drawing a lesson from Donald Trump's election campaign last year, Schulz said "the condemnation of entire groups of people must have no place in Germany."
SPD members also celebrated outgoing party chief, German Vice Chancellor Sigmar Gabriel, who used the occasion to speak out against the continuation of a coalition government after September elections.
Merkel's conservative CDU and their CSU sister party from the state of Bavaria currently form a grand coalition in Berlin with the SPD as a junior partner.
Gabriel told more than 600 party delegates in Berlin that he led the SPD into a coalition in 2013 "because the SPD isn't in politics to just have a look around."
"People want a new uprising," Gabriel said. "What they don't want is a continuation of the grand coalition."
Schulz was elected president of the European Parliament in 2012 and served in the role until January of this year, when he replaced Gabriel as SPD leader. His return to national politics in Germany from Brussels has boosted the SPD to a four-year polling record.
Merkel will be running for a fourth term in September.