Mazzarri, a midfielder and a product of Fiorentina's youth system, made his professional debut in 1981 for Pescara of Serie B, and played a short Serie A stint in Cagliari the following season, before being sold to Reggiana. He had his longest period at Empoli, who won promotion to Serie A for the first time during his time with the Tuscan side. After several spells with mostly minor teams, including a two-year stint with Acireale where he was part of the team who won a historic first promotion to Serie B, and then playing in the Italian second tier in 1993–94, Mazzarri ended his playing career in 1995 with Sassari Torres.