The 22-year-old 'Can I go with You' hitmaker, who is famous for her toned body, announced the partnership on her official website through a video message, reported media.
"I wanted to share some news with you because we're actually making it official with one of the great loves of my life... Diet Coke.
"The partnership is gonna include so many fun things having to do with the tour, having to do with Diet Coke in general, behind the scenes of the commercial shoot," she said.
In a statement, the Coca-Cola Company confirmed that the calorie-free drink had committed to long-term partnership with the singing superstar.
