Molinaro started playing at age 5 for Gelbison, in Vallo della Lucania, before growing up in the various Salernitana youth teams.

This marked the beginning of the two competitive seasons he played as a starter in Salerno, that included his first professional goal in 2004–05 in a match against Bari.

He made his debut in Serie A on 18 September 2005 in Siena - Palermo 1–2 and his first season in the top flight was characterised by ups and downs; losing the role of starting left-back to the more experienced Gianluca Falsini.

For 2006–07, Juventus, relegated to Serie B by the 2006 Italian football scandal, allowed Molinaro to remain at Siena (who sold Falsini), relying on him to cover the role of left-back.

On 20 June 2007, shortly before the transfer window deadline, Juventus redeemed him for a sum of €2.5 million.

With the arrival of Italy international Fabio Grosso and Uruguayan Martín Cáceres in the summer, Molinaro signed a loan deal with VfB Stuttgart on 5 January 2010 which initially saw him stay at the club until the end of the 2009–10 season.

[4] Juventus announced that on 14 June they received €3.9 million transfer fees and the deal was completed.

On 13 June 2022, Venezia announced Molinaro's retirement from playing and his appointment to the position of the team's technical director.