Williams was favoured to walk away with a clean sweep of the grand slams in 2014, but instead fell flat until the US Open where she triumphed on home soil.
Despite this, and an unconvincing start to the year, Henin believes that Williams enters next week's showpiece at Melbourne Park as the overwhelming favourite.
"If I had to tell you a name I would go with Serena Williams. If she is in form she just gives the impression none can beat her. She sure is the No.1 favorite to win in Melbourne this year," the Belgian has been quoted as saying by TennisWorld.
"It's up to her to decide whether she wants to win or not. If she really wants it, she is going to get it."
Eugenie Bouchard hit the headlines in Perth earlier in the month when she defeated Williams at the Hopman Cup, but Henin is not giving that result too much weight.
"Bouchard sure has a very captivating tennis. The public likes it a lot. She really brought new things to the sport of tennis. Of course, if you think of the match they played at the Hopman Cup I wouldn't take that too seriously. You can't really say that that event anticipates what is going to happen at the Australian Open," she said.
After Williams, Henin expects world number two, and former champion, Maria Sharapova, and world number three Simona Halep, to lead the charge, with the 32-year-old adding that: "Today, compared to ten years ago, there are a lot more players who can challenge the big names. I don't however expect any major surprise to win in Melbourne this year."