Knopf is currently the vice president and category head of Kraft Heinz's Planters nuts business, as well as a partner at Jorge Lemann's 3G Capital, which owns 23.9% of Kraft-Heinz - second only to Berkshire Hathaway's 27.7%.
Knopf will start in October, replacing current CFO Paulo Basilio.
Knopf previously worked at Goldman Sachs after graduating from Princeton in 2010. He joined 3G Capital in 2013 and started at Kraft Heinz in July 2015.
3G has a reputation for promoting young executives. Restaurant Brands International, 3G's second-biggest investment, is helmed by 37-year-old Daniel Schwartz, who was just 32 when he became CEO of Burger King. When the fast food chain merged with its Canadian neighbor Tim Hortons, he became CEO of the parent company.
Knopf made Forbes' 30-under-30 list this year for his role in the $11 billion Burger King-Tim Hortons merger and Heinz's merger with Kraft.
At Kraft Heinz, Knopf will have his work cut out for him. The company has not posted any sales growth since the 2015 merger. Since then, the Pittsburgh-based company been known more for cutting costs than expanding brands.
Earlier this year, Kraft Heinz attempted to acquire consumer goods conglomerate Unilever for $143 billion, but was rejected in what Berkshire Hathaway CEO Warren Buffett has called a "misunderstanding."
Shares of Kraft-Heinz were trading up fractions of a percent at midday in New York. Knopf did not immediately respond to a request for comment.
