The 31-year-old became the first woman to take part in a grand prix weekend for 22 years at Silverstone in July when she competed in a practise session.
However, engine failure ended Wolff's F1 debut after just four laps, but the former DTM driver is all set for a more prominent role under Felipe Massa and Valtteri Bottas at Williams next season.
"This is another step in the right direction for me," said Wolff
"I am delighted Williams are recognising my progression, hard work and that it is performance that counts.
"Williams is at a very exciting stage in its history and we are moving into 2015 with fantastic momentum, I'm proud to be part of the team.
"I'll be using my position to work closely with Felipe and Valtteri to make sure that the FW37 builds on the strong performance shown by the FW36."