With the Cubs in a season-long slump and playing .500 baseball, Manager Joe Maddon inserted the power hitting Rizzo into the lead-off spot in an away game against the New York Mets on June 13. In the next seven games the Cubs went 5–2 and Rizzo hit 4 home runs (3 to lead off a game). By June 20, Rizzo had reached base in the first inning in his first seven games as a leadoff hitter and became the first player to reach safely to start the first inning in his first seven career leadoff appearances in over half a century of Major League baseball. He had 12 hits in 28 at bats with 10 RBIs and hit .430 during the streak. Rizzo finished second behind the Nationals Ryan Zimmerman in a tight race for starting NL first baseman in the 2017 All-Star Game. On September 2, Rizzo became the fourth Cubs players to hit at least 30 home runs, 30 doubles, and 100 RBIs in three or more seasons; the others were Hack Wilson, Billy Williams, and Sammy Sosa.
Rizzo proposed to girlfriend Emily Vakos on June 1, 2017. They met when the Cubs were in Arizona for spring training 2016. The couple was married on December 29, 2018, with teammate Kris Bryant serving as one of the groomsmen. In 2020, he and his wife adopted a dog, which they named Kevin.