Zambrano's July numbers included a 1.38 ERA, tops in the Majors, and five wins, which tied him for the National League's best. He held three teams scoreless in six July starts and his 34 strikeouts during the month were second behind Giants pitcher Tim Lincecum.
Zambrano didn't allow more than five hits in any of the six starts, and surrendered just one homer.
He is two wins shy of matching a career-high 16 wins. Since June 6, he is 9-2 with a 1.41 ERA and 77 strikeouts.
"I think this is the best stretch I've ever had in my career," Zambrano said. "I feel good right now. Ever since I lost to the Pittsburgh Pirates in the last game of the first half, I feel comfortable on the mound, I feel confident. Hopefully I can keep doing a good job for my team."
Teammate Ted Lilly is doing his part, having made a push for Zambrano's award by matching his 5-1 record in July and posting a 2.52 ERA. Their combined efforts had the Cubs tied with Milwaukee atop the NL Central as of Thursday.
Other pitchers receiving votes this month were Lincecum (4-0, 1.62 ERA, 39 SO); Lilly (5-1, 2.52 ERA, 24 SO); Colorado's Aaron Cook (4-1, 2.68 ERA, 21 SO); Washington's Chad Cordero (9 SV, 1.29 ERA, 8 SO); and Billy Wagner (8 SV, 0.00 ERA) of the New York Mets.
Zambrano will receive a Sharp AQUOS full HD LCD-TV and a trophy as part of his award.
He may add more hardware once the season is finished.
"Any time I can do something for myself -- pitching, running, fielding, kicking the ball, whatever -- it's good for me," He said. "I have to be able to use what God gave me and use the ability."