Shares of the Seattle coffee-bar chain at last check traded 0.6% higher at $108.65.
“We’re pleased to bring Oatly oat milk to Starbucks stores nationwide in the U.S., something our customers have asked for as they increasingly seek a variety of plant-based choices,” Luigi Bonini, senior vice president of global product innovation at Starbucks, said in a statement.
Oatly's parent, Havre Global AB, said last week that it had confidentially filed to go public, Bloomberg reported.
The vegan milk company, backed by Oprah Winfrey and Jay-Z, will be listed after a review process by the Securities and Exchange Commission.
Starbucks has also added iced brown sugar oat milk shaken espresso and honey oat milk latte to its menu.
“We know from experience that we’re in the midst of a plant-based revolution,” Toni Petersson, Oatly's chief executive, said in a statement.
"With this next step, together we’re able to reach that many more people across the U.S. with oat milk and, in so doing, continue to do great things for the planet," Petersson added.
“People everywhere are looking for ways to eat and drink that are better for them and for the planet they live on. Oatly exists to make it easy for people to make those choices every day, with every cup of coffee."
Oatly, which entered the U.S. in 2017, also makes ice cream and yogurt.