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. In 1996, he settled in Pisa.[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.[2] He won with 10,515 votes e became a member of the Regional Council of Tuscany on 17 June 2015.[1] He was the promoter of the first regional law on startups and innovation and also promoted the establishment of the Tuscany Innovation Award, organized since 2017.[2][3]
In 2020, he is re-confirmed as a regional councilor with 12,720 votes and was elected president of the Regional Council of Tuscany on 19 October 2020.[2][4] In 2025, Mazzeo was re-elected to the Regional Council for his third consecutive term, receiving 13,274 votes.[5]