Born in Argentina, Castaldo joins Gaucho from a role as head chef at London’s Lanesborough Hotel, where he oversaw the Michelin-starred Celeste restaurant, and has previously cooked at Rosewood London, Sushisamba and Nobu London.
His CV also includes time at Lasarte in Barcelona, which holds three Michelin stars.
The chef's role at Gaucho will see him research and develop menus on an ongoing basis, as well as training staff.
His appointment follows a turbulent year for Gaucho, which fell in to administration last July resulting in the closure of all 22 sites of its sister concept Cau.
Gaucho was bought out of administration by Lomo Bidco, a conglomerate of banking and finance groups, in October with the steakhouse chains’ former managing director Martin Williams returning to head up the business.
The restaurant group reported an 8% growth in like for like covers in the four weeks of November 2018 after the introduction of lighter, less meaty dishes in an effort to attract younger diners.
Gaucho opened its first restaurant in Amsterdam in 1976 and launched in London in 1994. It now operates 16 UK restaurants, and has one in Dubai.