Arizona receives pitcher Luke Weaver, catcher Carson Kelly, infielder Andy Young, and a 2019 Competitive Balance Round B draft pick in return for the six-time All-Star, who is eligible for free agency at the end of 2019.
"We've been busy this offseason working to upgrade our lineup, and today we are excited to announce the acquisition of one of the game's premier players in first baseman Paul Goldschmidt," Cardinals president of baseball operations John Mozeliak said in a statement obtained by MLB.com's Chad Thornburg.
Since his sophomore MLB campaign in 2012, Goldschmidt has established himself as one of baseball's best first basemen. He's finished in the top three in NL MVP voting on three occasions and is the owner of a trio of Gold Gloves and four Silver Sluggers.
"This was an extremely difficult decision given how much Paul has meant to our team both on and off the field," Diamondbacks president and CEO Derrick Hall said in a statement. "He represents everything it means to be a D-back, and we are very thankful to him for all that he has done for our franchise and our fans. We wish him, Amy and their family nothing but the best in the years ahead."
Weaver, 25, was selected 27th overall in the 2014 draft. He pitched in 30 games - 25 starts - for St. Louis last season.
Luke Weaver's Career Stats
The 24-year-old Kelly has only appeared in 63 games at the major-league level because he was blocked by veteran stalwart Yadier Molina. He owns a career .154/.227/.188 line with 10 RBIs in parts of three seasons.
Young, 24, was a 37th-round draft choice in 2016. He advanced as high as Double-A last season, hitting .289/.379/.479 across multiple levels. He wasn't among MLB Pipeline's top 30 Cardinals prospects before the trade.