She will have an increased simulator programme at Williams' Grove base this year as well as “continu[ing] to be fully immersed within the team both trackside at certain grands prix and at the factory,” according to the its announcement.
Chadwick was already slated to attend at least eight grands prix in her capacity as a competitor in the W Series, which holds its second season exclusively at F1 events.
“I have absolutely loved my time with Williams so far and could not be more delighted to continue working with the team in my role as development driver,” said the 22-year-old.
“I feel I am improving as a driver all the time, and my time spent in the simulator this coming season will prove to be invaluable.
“I look forward to fully immersing myself at Williams once again this year.”
Team principal Simon Roberts added, “We are delighted that Jamie will continue as a development driver for the team.
“Jamie's determination and drive to do more, as well as push the boundaries, is something we admire at Williams and we are all looking forward to the year ahead with Jamie as part of the team.”
As well as the W Series title, Chadwick's achievements include firsts for a female driver such as a British Formula 3 race win, in 2018; the MRF Winter Series title, in 2018/19; the British GT GT4 title, in 2015; and a class win at the Nurburgring 24 Hour.
The Briton's Williams role includes supporting the team with its media and marketing activities, while she will also tackle the first ever season of Extreme E, an electric off-road championship, in 2021 with Veloce Racing.
Extreme E kicks off in Saudi Arabia on April 3-4 while W Series' opening round will be held at the French Grand Prix, which takes place on June 25-27.