Ebert was born in Heidelberg, Baden, German Empire on 4 February 1871 as the seventh of nine children of the tailor Karl Ebert (1834–92) and his wife Katharina (née Hinkel; 1834–1897). Three of his siblings died at a young age. Although he wanted to attend university, this proved impossible due to the lack of funds of his family. Instead, he trained as a saddle-maker from 1885 to 1888. After he became a journeyman in 1889 he travelled, according to the German custom, from place to place in Germany, seeing the country and learning fresh details of his trade. In Mannheim, he was introduced by an uncle to the Social Democratic Party, joining it in 1889. Although Ebert studied the writings of Karl Marx and Friedrich Engels, he was less interested in ideology than in practical and organisational issues that would improve the lot of the workers then and there. Ebert was on the "black list" of the police due to his political activities, so he kept changing his place of residence. Between 1889 and 1891 he lived in Kassel, Braunschweig, Elberfeld-Barmen, Remscheid, Quakenbrück and Bremen, where he founded and chaired local chapters of the Sattlerverband (Association of Saddlers).
After settling in Bremen in 1891, Ebert made a living doing odd jobs. In 1893, he obtained an editorial post on the socialist Bremer Bürgerzeitung. In May 1894, he married Louise Rump (1873–1955), a manual labourer, who had been employed as a housemaid and in labelling boxes and who was active in union work. He then became a pub owner that became a centre of socialist and union activity and was elected party chairman of the Bremen SPD. In 1900, Ebert was appointed a trade-union secretary (Arbeitersekretär) and elected a member of the Bremer Bürgerschaft (comitia of citizens) as representative of the Social Democratic Party. In 1904, Ebert presided over the national convention of the party in Bremen and became better known to a wider public. He became a leader of the "moderate" wing of the Social Democratic Party and in 1905 Secretary-General of the SPD, at which point he moved to Berlin. At the time, he was the youngest member of the Parteivorstand (party executive).
Meanwhile, Ebert had run for a Reichstag (parliament of Germany) seat several times in constituencies where the SPD had no chance of winning: 1898 Vechta (Oldenburg), 1903 and 1906 Stade (Province of Hanover). However, in 1912, he was elected to the Reichstag for the constituency of Elberfeld-Barmen (today part of Wuppertal). This was the election that also made the SPD the strongest party in the Reichstag with 110 out of a total of 397 members, surpassing the Centre Party. On the death of August Bebel on 13 August 1913, Ebert was elected as joint party chairman at the convention in Jena on 20 September with 433 out of 473 votes. His co-chairman was Hugo Haase.
Friedrich Ebert with his wife Louise and their children (from left to right) Friedrich, Georg and Heinrich (Christmas 1898)