The Cubs starting pitcher hit his first home run of the season and 21st of his career in the fifth inning of Monday night's 14-2 win against the Pirates' Brian Burres.
Zambrano connected on a 1-0 pitch to drive in Koyie Hill. It was his first home run since Aug. 25, 2009, when Big Z connected off the Nationals' Garrett Mock.
Zambrano, who was batting .206 this season with seven hits in 34 at-bats prior to Monday's game, holds the Cubs' record for most home runs by a pitcher. Hall of Famer Fergie Jenkins is second with 13.