She replaces Howell James, who left last summer.
In her new role, Manson will be responsible for overseeing all internal and external comms for the company.
Manson has been with the company for 20 years, based in London and New York. From 2009 she served as deputy global head of corporate comms and most recently has been international director for corporate affairs.
Manson has worked on campaigns covering the arts market and luxury fields, as well supporting high-profile single owner collection sales plus celebrity and charity auctions. She also helped to launch the company in China, the Middle East, India and Russia as part of a strategy to develop new markets.
Manson said: "It is a huge honour to lead the exceptionally dedicated and creative global communications team at Christie’s. As art continues to command such attention in the world, we are committed to working hard to share our stories about art and Christie’s in the most international, creative and capable way."