Mazzeo was born in Melfi, province of Potenza, on 22 February 1977, to a family from Barile.
He obtained a degree in electronic engineering from the University of Pisa and later a master's in Innovation Management at the Sant'Anna School of Advanced Studies, after which he started a business in the field of medical diagnostics.
[2] A member of the Democratic Party since 2007, he was elected as a city councilor in Pisa in 2008, also serving as the president of the budget committee.
[1] Elected as a member of the party's assembly and regional board in 2009, from 2013 to 2018 he was a member of the National Assembly of the party and from July 2015 to March 2018 he served as the deputy secretary of the Tuscan branch.
[2] In 2015, Mazzeo was a candidate in the Tuscan regional elections in the Pisa constituency.