The firms joined in January to create a provider of consumer and corrugated packaging in a deal with a combined equity value of $16bn.
Steve Voorhees, who will be the chief executive officer of WestRock Company, said the name draws on the strongest elements from the legacy names.
"The name speaks to our determination to build on the long track record of success and growth that has been established by both companies," he said.
“WestRock's aspiration is to be the premier partner and unrivaled provider of winning paper and packaging solutions for our customers."
The pending combination has received antitrust approval in the US and is awaiting other regulatory and shareholder approvals expected in June.
WestRock's 42,000 team members will support customers around the world from more than 300 operating facilities spanning North America, South America, Europe and Asia.