In 25 games last month, Rizzo led NL rookies in hits (32), home runs (seven), RBIs (17) and total bases (55) while ranking second in runs scored (14). He also finished third among NL rookies with a .330 batting average, .375 on-base percentage and .567 slugging percentage.
Rizzo's seven homers were the most by a Cubs rookie in a calendar month since Mel Hall hit nine in August 1983.
The 22-year-old Rizzo also proved to be calm in the clutch, driving in eight go-ahead runs in July and producing four game-winning RBIs, leading NL rookies in both categories. He registered his first walk-off home run on July 29 with a two-run homer in the bottom of the 10th against the rival Cardinals.
That clutch production started from the get-go, as he became the first player in Cubs history to collect three game-winning RBIs in his first five games with the team.
Rizzo also had nine multi-hit games in July -- including a career-high four-hit game on July 6 -- and hit safely in 20 of his 25 games.
Rizzo, who was acquired by the Cubs from San Diego during the offseason for right-hander Andrew Cashner and Minor League pitcher Zach Cates, is the fourth Cub to win the award, joining Hee-Sop Choi (April 2003), Geovany Soto (April and August 2008) and Darwin Barney (2011).