As general manager, he will be responsible for operations and managing the day-to-day demands of the 142-room hotel.
Voco St. David's also reopened its spa following a £300,000 refurbishment and renovated hotel bar and restaurant Tir a Môr.
Grimm said: "My utmost goal is to maintain our leadership in the luxury lifestyle hotel market, not only in Cardiff but nationally. I've been given a very warm Welsh welcome by the team and am very much looking forward to continuing to build on the success of my predecessor, Mark Gallagher."
Voco launched in 2018 and falls under IHG Hotels & Resorts' premium collection.
