Liashko was born in Chernihiv on 3 December 1972,[1] but grew up in the village of Lozovivka in Starobilsk Raion, where his mother lived.

[7] When he graduated from boarding school, Liashko had around 2,000 roubles in savings, the value of which was completely wiped out by post-Soviet inflation.

[1] In 1999, the publication was closed by decision of the Moscow District Court in Kyiv for "divulging state secrets".

[1] During this term he served as Chairman of the Subcommittee on the organization of the Supreme Council of the Parliamentary Committee on Rules, Ethics and maintenance of the parliament.

[2] YTB had previously stated that a video leaked a week before would not be the reason for excluding of Liashko from the faction.

[10] In the 2012 parliamentary election, he was re-elected to the Verkhovna Rada after winning single-member constituency number 208 in the Chernihiv Oblast (as candidate of the Radical Party) with 55.57% of the votes.

[1] In mid-November 2012, Liashko went on hunger strike in support of jailed fellow opposition leader Yulia Tymoshenko, and against the recognition of the results of the 2012 parliamentary election.

[12] During the Russian annexation of Crimea in 2014, he introduced a bill which classified participants of the "separatist rallies for joining Russia", as well as those who obstruct the movement of soldiers and military equipment, to be saboteurs and accomplices of the occupiers.

The bill provided for the introduction of a visa regime with Russia, denunciation of the agreements made with Russia, the prohibition of the Communist Party of Ukraine and the Party of Regions, called for the EU to ban the entry of Crimean residents with Russian passports and other events.

[13][14][nb 1] During the 2014 pro-Russian conflict in Ukraine and two days before the 25 May 2014 presidential election, Liashko claimed responsibility for the storming of a local government building in Torez (by "Soldiers from the Liashko Battalion 'Ukraine'") that killed a pro-Russian separatist and supporter of the self-proclaimed Donetsk People's Republic while critically wounding another.

Amnesty International, while noting "abuses perpetrated by both sides of the conflict", pointed to Liashko as "one particularly errant MP" who published videos of his actions on his website.

[28] Liashko took 31.78% of the vote, while his closest rival, Anatolii Hunko [uk] from Servant of the People won with 34.10%.

[29] In early October 2022 Liashko posted a video seemingly showing him taking the oath of induction into the Armed Forces of Ukraine.

[32] In 2016, a special investigation conducted by Radio Liberty recorded the facts of secret meetings between Oleh Liashko and Rinat Akhmetov.

[33] In February 2018, the former director of a Mariupol factory belonging to the Metinvest group, Yurii Zinchenko headed the executive committee of the Radical Party of Oleh Liashko.

[35] Liashko makes frequent appearances during broadcasts of the TV channel Ukraine, which belongs to Akhmetov.

Liashko was handed a mobile phone, spoke to the supposed friend and then promised to beat his face in while being filmed on camera.