[1] He was the co-leader of the left-wing pro-Kurdish Peoples' Democratic Party (HDP), serving alongside Figen Yüksekdağ from 2014 to 2018.

[4] In a judgement given in December 2020, the European Court of Human Rights judged that, given "the timing of [Demirtaş] continued detention (coinciding with an important constitutional referendum and the presidential election)" and Turkey's "systemic trend of “gagging” dissenting voices", Demirtaş's continued pre-trial detention's political purpose had been predominant".

From 1991 he studied maritime commerce and management at the Dokuz Eylül University,[6] where he would face political problems that would force him to leave school without finishing his degree.

He cites his experience at the funeral of politician and human right lawyer Vedat Aydın (1953–1991) as a political awakening: I became a different person.

As such he supported the abolition of the restrictions against education in the Kurdish language and demanded equal rights for Turks and Kurds in the Turkish constitution.

[9] When in October 2007[10] an article published in the Bolu Ekspress demanded politicians of the DTP to be killed for deaths caused by the Kurdistan Workers' Party (PKK) he filed a complaint but the court decided it fell into the bounds of "freedom of thought" in 2008.

Demirtaş contested the 2011 elections as part of the joint 'Labor, Democracy and Freedom' list endorsed by the BDP and 18 different democratic political organizations, this time for Hakkari.

[14] At a rally in the Kızıltepe district of Mardin in November 2012, Demirtaş criticized the Turkish police for intervening after marchers carried posters of Abdullah Öcalan, saying "I call on you, those who are not bothered about the Kurds’ killer Evren’s statue being erected [or by] schools named after Evren.

"[15][16] In 2019, Demirtaş defended his statement in court, arguing that he was responding to how posters were met with panzers and truncheons, and that he is opposed to erecting statues of Öcalan.

[19] In 2014 Demirtaş and Figen Yüksekdağ were elected as the co-chairs of the Peoples' Democratic Party (HDP) – a new initiative originating from a three-year-old coalition of the BDP and various different political parties and organization under the auspices of the Peoples' Democratic Congress (HDK) - for the 2014 presidential elections of Turkey, being one of three candidates and hoping to attract left-wing voters.

He stressed that gender equality and a women's quota is preeminent in their party program for the elections and announced in October 2013, that for the Metropolis Diyarbakır a female mayor was planned.

The international press characterized Demirtaş as the 'Kurdish Obama' and supporters of the HDP took to the street to celebrate their success on the evening of polling day.

[42] Party leader Pervin Buldan declared that Demirtaş, the jailed former co-chair of the HDP, would be leading a five-party "Kurdish alliance" into the general election.

The criminal indictment against Demirtaş alleged that in a public statement on the 6 October, the HDP raised support for protests against claimed approach of the Turkish Government shows towards the Islamic State (IS) attack on Kobane.

[45] President Recep Tayyip Erdogan blamed Demirtaş for provoking protests, and said that all Kurdish people are the citizens of Republic of Turkey, and no one can attempt to build a state for them.

[50] On 20 November 2018 the European Court of Human Rights (ECHR) ruled Demirtaş should be released from preliminary detention,[51] and ordered Turkey to pay him 25'000 Euros.

[5] The Court deemed the lifting of the parliamentary immunity and the subsequent pre-trial detentions as politically motivated because this step came only after the governing Justice and Development Party (AKP) had lost its majority in parliament.

[59] ECHR called for releasing Demirtaş and stated that his arrest in 2016 violated his freedom of speech and the right of joining to the elections.

[62] As his wife informed the public on in an interview with Ismail Küçükkaya on FOX TV about it, the Radio and Television Supreme Council (RTÜK) initiated an investigation on the program due to her remarks.

[66] After extending his mandate in 2023 elections, President Recep Tayyip Erdoğan said that releasing Demirtaş would not be possible under his governance.

[1] Demirtaş has faced threats due to his political activity and on November 22, 2015, he survived an assassination attempt.