The couple were married at a medieval church overlooking Tuscany's Montalcino valley.
Verlander tweeted about the wedding on Monday.
Verlander's Astros beat the Los Angeles Dodgers in Wednesday's decisive Game 7 for their first World Series championship in franchise history.
Verlander, 34, and Upton, 25, missed the team's celebratory parade Friday in Houston due to the impending nuptials.
The two got engaged in 2016 after dating on-and-off for three years.
Keuchel records rally for absent Verlander
Dallas Keuchel records the crowd cheering for Justin Verlander at the Astros' World Series rally since the righty is in Italy for his wedding.