Moritz succeeds Dennis Nally, who will retire this June after a 42-year career with PwC.
"Bob brings a strong sense of purpose, strategic leadership and business insight. His clear focus on all stakeholders is critical to the successful future of our worldwide network," said John G Maxwell, chairman of PwC's Global Board.
Moritz has been with PwC his entire career, joining in 1985 and becoming a partner in 1995. Since 2009, he has led PwC US as its chairman and senior partner, PwC said in a statement.
Moritz has held a number of leadership roles within PwC, including leading the US Assurance practice as well as serving as the managing partner for the New York region.
Moritz's successor as chairman of PwC US will be announced later this year, following an election process, the statement added.