Venus, currently ranked 11th in the world, will be promoted to third seed ahead of former champions Jennifer Capriati and Lindsay Davenport following a recommendation by the Women's Tennis Association.
The Australian Open has traditionally chosen its seeds according to their world rankings but tournament director Paul McNamee said they were making an exception for Venus.
"Venus will be seeded three behind Justine Henin-Hardenne and Kim Clijsters under a special seeding which the WTA had recommended for the next group of tournaments," McNamee told reporters.
A former world number one, Venus hasn't played a competitive match since losing to Serena in last year's Wimbledon final but made her comeback in an exhibition tournament in Hong Kong this week.
McNamee said current world number one Henin-Hardenne would be the top seed for the event starting in Melbourne on January 19, ahead of her Belgian compatriot Clijsters, who is still in doubt after injuring her ankle at the Hopman Cup in Perth.
"Whilst it's obviously disappointing to hear that Serena hasn't recovered in time to defend her title, it's great to see that Venus is back playing competitive tennis after her own long-term injury," McNamee said.
"I'm sure the crowds will be looking forward to welcoming her back to Melbourne Park after her six month absence from the Tour and her seeding reflects that she's obviously back and playing great tennis."
Venus hasn't won a grand slam title since her victory in the 2001 U.S. Open but has lost five finals to Serena following that win, including last year's Australian Open.
That was her best performance in five appearances at Melbourne Park but her chances of going one better this year have been boosted by her elevated seeding and the withdrawal of most of the big names.
Four-times champion Monica Seles has not entered the event and both Capriati and Clijsters are in doubt because of injuries.
Serena, who would have been third seed, announced on Saturday she was officially pulling out.
