Dave Wheater will join the Grove-based squad from Lotus to become head of aerodynamic performance. He will report to head of aerodynamics Jason Somerville.
Shaun Whitehead, who previously worked at Red Bull, joins Williams as head of aerodynamic process. Somerville described the duo as "first class talents."
"These two appointments show our commitment to both improving the process of aerodynamic development while focusing on the application of that development to true on-track performance," added the team's chief technical officer Pat Symonds.
"Dave and Shaun bring a wealth of experience to our team and I welcome them both to Grove and fully expect them to make significant contributions to the renewed competitiveness that we are all working so hard to achieve.
"With Dave and Shaun on board, and under Jason's stewardship, we will be well positioned to make gains in this important area and support the continuing task of developing the FW36 in what promises to be an exciting year for the sport in 2014."
Williams had originally targeted Dirk de Beer, who opted to join Ferrari instead. Wheater was de Beer's deputy at Lotus.