The win continues a good week for Arnold, which yesterday was named as one of two roster agencies alongside Interpublic Group's Mullen, on the $100m (£70m) Alberto Culver creative account.
The agency takes immediate responsibility for Alberto Culver's St. Ives and Noxzema skincare account, as well as the Nexxus hair-care brand.
The Havas-owned agency already has experience of working within the sportswear category, having worked on briefs for Nike and American football team the Miami Dolphins.
Andrew Benett, Global CEO of Arnold Worldwide and global chief strategy officer of Havas Worldwide, said: "New Balance is one of those great brands that every agency wants to work with.
"It's a company devoted to innovation, technology and, above all else, its valued customers. We couldn't be more excited to partner with New Balance and help shape its next chapter of success."
Arnold's portfolio of clients includes Fidelity Investments, The Hershey Company, Jack Daniel's, McDonald's and Ocean Spray.
The New Balance media account is handled by Omnicom's PHD Group globally. It has held the account since 2008.