[19] After the establishment of "Right Sector" in Odesa on February 5, 2014, on March 22 of the same year, he was appointed to head the regional branch of the organization.

On September 30, 2014, he participated, along with other activists of the Right Sector, Automaidan, Euromaidan, and Self-Defense, in the "trash lustration" of Nestor Shufrych, who came to Odesa for a meeting of the "Opposition Bloc" party.

[21][22] Sternenko took part in many other activities in Odesa during this time, including: shutting off spice drug trafficking circles in Odesa by Right Sector,[23] the disruption of the concerts of Ani Lorak and Svitlana Loboda in Odesa in 2014,[20] the picketing of the Russian consulate, the blockade of the occupied Crimea in the fall of 2015, the criminal prosecution of Igor Bychkov (caught for bribing the head doctor of the Rozdilnya Central District Hospital, who was sentenced to five years), assisting in the conviction of Valentin Dubovenko (involved in corruption schemes and abuse of official position),[24] and other measures.

[25] On September 13, 2015, in Odesa, Sternenko was one of the organizers of the "March in Support of Political Prisoners" for Andrey Medvedko and Denis Polischuk, who were accused of murdering pro-Russian commentator Oles Buzina.

The activist voluntarily handed to law enforcement officials his air gun, a collectible knife, and a noise pistol.

[27] Shcherbych was a deputy of the Lyman Raion Council for the pro-Russian Rodina party who was accused of organising so-called titushky (criminal gangs hired to beat up anti-government protesters).

[28] On November 15, 2016, he appealed to the court with a lawsuit against a professor of the Faculty of History of Odesa National University, Olena Radzikhovska.

On November 24, the Odesa Primorskyi District Court chose a preventive measure for the activist in the form of detention for a period of 60 days with the alternative of posting bail in the amount of UAH 600,000.

[35] He was among the organizers of the protest action "Avakov is the devil", which took place on August 28, 2019, in Kyiv near the Office of the President of Ukraine.

[37] On 9 October 2019, the General Prosecutor's Office of Ukraine sent a criminal case involving attacks on civil activist Serhii Sternenko in Odesa to the Main Investigation Directorate of the SBU to check the information about the possible involvement of local authorities and police of the Odesa city.

[41][42] A week after her appointment on 25 March 2020, the new Prosecutor General of Ukraine Iryna Venediktova held a formal meeting with the Minister of Internal Affairs Arsen Avakov to discuss the case about attack on Sternenko, but called it as the notorious case about murder of Ivan Kuznetsov.

[12] On 23 February 2021 a court in Odesa found Sternenko and Ruslan Demchuk[44] guilty of the abduction of Serhii Shcherbych and the illegal possession of arms.

On February 24, 2022, when Russia's full-scale invasion of Ukraine began, Sternenko joined the "Honor" unit, which is part of the Special Operations Forces.

Later, the frontman of the band Antytila Taras Topolya, soldier and writer Valeriy Markus [uk], the head of the Luhansk regional military administration Serhiy Haidai, the poet Yevhen Rybchynskyi, tennis player Sergiy Stakhovsky and others joined his initiative.

[49] Sternenko runs his own video blog on YouTube, where he talks about events in Ukraine, including the war.

It won a Palianytsia Award for Man of the Year in Ukrainian YouTube from the editorial office of Toronto Television in 2020.