Pellegrini's great-grandfather was Italian. He studied at the Faculty of Economics of Matej Bel University and the Technical University of Košice, focusing on banking, investment and finance at the latter. 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.
On 25 November 2014, he was elected Speaker of the National Council, succeeding Pavol Paška. In 2015, he was appointed Digital Champion of Slovakia, a European Union appointed position to promote the benefits of an inclusive digital society.
Made Deputy Prime Minister for Investments in 2016, under Prime Minister Robert Fico, Pellegrini was sworn in as head of government after his predecessor resigned on 15 March 2018 in the wake of the murder of journalist Ján Kuciak. President Andrej Kiska approved of Pellegrini's Cabinet on 21 March 2018; 81 members of the National Council voted in favour of approving the cabinet the next week. on 26 February 2020 After serving as Acting Interior Minister in April 2018, Pellegrini temporarily took on the role of Finance Minister when Peter Kažimír left to become Governor of the National Bank of Slovakia in 2019. Later, in December 2019, he assumed the office of Minister of Health after Andrea Kalavská resigned. His party lost the 2020 parliamentary election to the populist, anti-corruption party Ordinary People led by Igor Matovič. During the COVID-19 pandemic, as medical supplies began to dwindle, nations began competing for supplies outside their jurisdictions, either paying companies to reroute or seizing equipment intended for other countries. Pellegrini said he booked two million masks from Ukraine, the requirement was payment in cash. However, a German agent appeared, paid more for the masks, and bought them. Ukraine Foreign Affairs MinisterDmytro Kuleba responded to the situation by saying there was no country in Europe that would not hunt face masks and respirators around the world.
Personal life
Pellegrini has Italian roots. His great-grandfather Leopoldo Pellegrini came to the Austro-Hungarian Empire to participate in the construction of the railway between Levice and Zvolen. He then decided to settle in Lehôtka pod Brehmi, in the district of Žiar nad Hronom, after falling in love with a local girl, Maria Kunovská.