Tournament director Craig Tiley released a statement Thursday saying Williams had withdrawn from the Hopman Cup international mixed teams competition in Perth and the Australian Open in January.
It will be the second consecutive major Williams will miss, and the loss of 2,000 rankings points could cost the 29-year-old American her place in the top 10.
Williams has only played one exhibition match since winning at Wimbledon last year. She had surgery after cutting her foot on broken glass at a restaurant following her title at Wimbledon. She returned to practice in September but twice put off her comeback, missing the U.S. Open, the season-ending WTA tournament, the Fed Cup and a handful of tour-level events.
She said she had more surgery last month and couldn't risk returning before the injury had properly healed.
"As I recently learned, pushing myself back into my intense training too early only caused me further injury and damage," Williams was quoted as saying. "While I desperately want to be back on the court and competing in the first Grand Slam tournament of the year, it is imperative for my health that I continue to work with my doctors to ensure my foot heals properly.