[1] Pellegrini is the first Slovak politician to have held all three highest constitutional posts (President, Prime Minister and Speaker of Parliament) in the country.

[3] Between 2002 and 2006, he worked as an economist and later as advisor to National Council member for Privatization and Economy Ľubomír Vážny, supported by ĽS-HZDS, SNS and Smer-SD.

[3][4] He started his political career in 2002 at the age of 26 when he ran for the first time in the parliamentary elections for the party Direction – Social Democracy from 41st place and received 1,223 votes, which was not enough for him to become a deputy National Council of the SR.

In the 2010 Slovak parliamentary election, he again ran for the Smer-SD party from the 34th place in the candidate list and with a gain of 2,745 votes became a member of the National Council.

Ukraine Foreign Affairs Minister Dmytro Kuleba responded to the situation by saying there was no country in Europe that would not hunt medical masks and respirators around the world.

[25] On 23 March 2024, he came second in the first round with 37.03% with career diplomat Ivan Korčok winning with 42.52% and retired lawyer and judge Štefan Harabin claiming third with 11.74%.

[26] Soon after being second, he had claimed support from coalition partners SNS, whose leader Andrej Danko, withdrew from the first round, as well as unsuccessful candidates Krisztián Forró and Ján Kubiš.

[28] On the day after the election, he confirmed that he will resign as leader of HLAS-SD and withdraw his membership of the party to honour the unwritten political tradition of the president being a nonpartisan officeholder.

[31] His great-grandfather Leopoldo Pellegrini (1856–1942) of Salter (Trentino Region), which at the time was also part of the Austria-Hungarian Empire, came to Slovakia to participate in the construction of the railway between Levice and Zvolen.

The incident led to the resignation of the magazine's editor, who alleged that Pellegrini had intervened to stop the question from being published.