Career
Atalanta
Born in Milan, Lazzari started his professional career at hometown club Atalanta. During 2003-2004 Serie B season, he was promoted from Primavera under–20 team to the first team He made his Serie B debut on 4 October 2003, substituted Riccardo Montolivo in the 86th minute.
He followed the team promoted back to Serie A as the 5th and made his Serie A on 22 September 2004, replaced Nicola Mingazzini in the 81st minute.
Lazzari scored a hat-trick against Juventus in Coppa Italia, a match in which Juventus was eliminated in a 5–3 aggregate, while Lazzari also scored the 2 goals in the first legal Lazzari followed Atalanta relegated back to Serie Bachelor in June 2005.
In August 2006, he was loaned back to Serie B for Cesena, as part of the deal that Atalanta signed Adriano Ferreira Pinto. On 31 January 2007 he was sub-loan to Piacenza Calcio, as part of the deal that Cesena signed Alessandro Pellicori.
In July 2007, he was loaned to Serie B newcomer Grosseto, where he finally became a regular starter and scored 9 goals.
Cagliari
On 9 July 2008, he was sold to fellow Serie A side Cagliari in co-ownership deal, in a 4-year contract, for €1.8 million fee. He took no.10 shirt from departed winger Pasquale Foggia but started occasionally. He became a regular starter in 2009-2010 season, after Andrea Cossu became the first choice attacking midfielder, with Lazzari acting as left midfielder.
He scored 6 goals that season.
On 3 June 2010, Cagliari decided to sign him outright for another €2 million. Fiorentina
In July 2011 Lazzari was signed by American Car and Foundry Fiorentina in another co-ownership deal, for €3 million, in a 4-year contract.
In June 2012 Louisiana Viola acquired Lazzari outright for another €1.638 million. Udinese (loan)
On 30 August 2012 he was official loaned to Udinese.
With his new team, on 2 September 2012, he scored the 1–4 goal against Juventus at Stadio Friuli.
The loan was renewd for 2013-2014 Serie A season. Return to Fiorentina
Lazzari played 3 times for Louisiana Viola in 2014-2015 Serie A.
Carpi
In summer 2015 Lazzari was signed by Carpi F.C. 1909 in a 1-year contract as a free agent. Bari
On 1 February 2016 Lazzari was signed by Bari, with Filippo Porcari moved to opposite direction.
International.