He is a trained retail salesman and became an official in Gewerkschaft Handel, Banken und Versicherungen (HBV), the union for trade, bank and insurance employees during the 1980s.

In the Thuringia state election in September 2009 he led The Left to become the second biggest party with 27.4% of the votes, making him a competitor for the post of minister president.

In 2003, it became publicly known that Germany's domestic intelligence service, the Bundesamt für Verfassungsschutz, had been observing Ramelow and had opened a file on him because of his alleged contacts with the German Communist Party (DKP) during the 1980s.

Supposedly the observation had stopped following Ramelow's entry into the Landtag in 1999, but in May 2006 the Administrative court of Weimar decreed that the Thuringian State Verfassungsschutz had to reveal the file and the stored data.

Ramelow sued the authorities, but in 2010 the Federal Administrative Court of Germany ruled that the Verfassungsschutz is entitled to observe politicians of the Left Party due to "reasonable suspicion of anti-constitutional activity".

[7] After it surfaced that Kemmerich may have cooperated with AfD leader Björn Höcke to win the election, Ramelow published a tweet with a photo of Adolf Hitler shaking hands with Paul von Hindenburg during his inauguration as Chancellor alongside a photo of Höcke shaking hands with Kemmerich.

[12] In January 2021, as Thuringia became Germany's worst affected state, Ramelow announced that he regretted this decision and now supported a hard lockdown.

[12] Ramelow was voted out of office following the 2024 Thuringian state election, in which the red-red-green minority coalition lost more seats and The Left was overtaken by the AfD as the largest party.