Arena joins Joseph with more than 30 years experience, most recently as JW Anderson director of product and design for ready-to-wear, accessories and catwalks.
He has also held the position of director of design and innovation for ready-to-wear and accessories at Hungarian fashion label Nanushka and head of ready-to-wear for London Fashion Week designer Christopher Kane.
Arena will be based in London in Joseph's new design office at its Fulham headquarters, which houses a newly-appointed design team, atelier, product development team and production team.
His first collection for Joseph will be spring/summer 26, which will arrive in stores in October 2025.
Arena said: “I am honoured to join Joseph as creative director.
“The rich heritage and timeless design codes have always been an inspiration to me in my career. I look forward to bringing to life a new vision for this iconic brand.”
Joseph CEO Barbara Campos said: “[Arena] is a highly talented creative and has a wealth of experience within contemporary luxury.
“I look forward to working with Mario as we enter this exciting new chapter.”