Ciampi has replaced Joanne Taylor-Stagg, who had been at the hotel for two years and is yet to announce her next move.
He has arrived in London after spending two years as general manager at the Scrub Island Resort, Spa & Marina, which operates under Marriott's Autograph Collection in the British Virgin Islands.
Ciampi's last role in the UK was as general manager at the V&A Manchester Marriott hotel from 2015 to 2016, having previously overseen the relaunch of the Glasshouse hotel in Edinburgh in the same role.
Ciampi, who a holds a master certification in hotel management from Cornell University, New York, said he was delighted to join the hotel. "Its dynamic overhaul in 2017 transformed its aesthetic and its ethos, to create a hotel that both Londoners and tourists could be equally proud of. I want to continue to build on this as the hotel enters its exciting next phase; and I am determined and committed to taking it to the next level."
The transformation of the Trafalgar St. James - owned by L+R, headed by property developer brothers Ian and Richard Livingstone - included the creation of the Trafalgar Dining Rooms restaurant, the new Bibilo private lounge and the extension of a year-round alfresco Rooftop bar.