Jussi Pylkkänen, who has been with the company since 1986, has become global president and Stephen Brooks global chief operating officer, both effective immediately.
Mr Pylkkänen will be responsible for the global management of Christie's Art specialist community and for the global development of client engagement, leading all client-facing activities of Christie's in all regions.
Most recently he was president and chairman of Christie's in Europe, the Middle East and Russia.
Until now Mr Brooks, initially appointed CFO in 2009 and then COO in 2012, has overseen most of Christie's support functions, including the commercial management of auction, private sale and eCommerce channels as well as infrastructure. He now adds responsibility for day-to-day management of corporate activity, global infrastructure and risk planning.
Meanwhile, Doug Woodham is to quit his post as president of Christie's America at the end of the year.