Wolff, whose husband Toto quit Williams' board of directors last week to join Mercedes, was appointed development driver 10 months ago for the Grove-based marque.
Throughout the coming campaign the 30-year-old Scot's level of involvement will see her undergo an increased programme in the team's simulator combined with a greater level of in-car testing.
In particular, Wolff will drive the FW35 at Idiada, Spain, next month ahead of the team's official launch in Barcelona on February 19.
Wolff said: "I really enjoy my time working with Williams and feel very much at home here.
"Last year was a valuable experience and I certainly feel I've developed a lot as a driver.
"Increasing my role this year will further this progression, and I can't wait to get behind the wheel of the car for the first time next month.
"I'm showing women can play a role at the top level of motorsport and would like to thank Sir Frank Williams and the whole of the technical team for the trust they continue to show in me."
Explaining the team's decision, technical director Mike Coughlan said: "Susie has proved herself to be a valuable addition to our driver roster and her feedback during simulator sessions is second to none.
"As a result we will be stepping up her role this year, and I'm looking forward to the progress we can make with Susie's input in conjunction with that of Pastor and Valtteri."