Every time the American has made the final at Melbourne Park she has gone on to win the Daphne Akhurst Memorial Cup.
Victory in Saturday's final against either seventh seed Angelique Kerber or unseeded Briton Johanna Konta, would give her a 22nd grand slam title, moving her to a tie with Steffi Graf for the most in the Open era.
Williams romped through the first set in just 20 minutes before Radwanska showed some fight in the second but she was unable to stop the momentum of the American, who clinched her place in the final in 64 minutes.
"I'm really excited to be in another final. It blows my mind right now," Williams said in a courtside interview. "I just feel like I'm being the best I can and I can't believe I'm in another final.
"She started really well in the second set and making some great shots and hitting it deep and I just thought that I had to be aggressive."
Williams began in ominous fashion breaking the Pole's serve in the first game with Radwanska's lack of power highlighted by the blistering nature of the American's returns.
Radwanska's fastest serve in the first game reached just 140 kph. Williams was returning the ball at over 130.
The fourth seed appeared resigned to defeat in the first set by the fourth game. She barely got a backhand return to a Williams serve then stood, with slumping shoulders, and watched as the 34-year-old put the overhead smash away.
Williams cleaned up the first set in just 20 minutes before Radwanska elicited the largest cheer of the match at that time when she held serve in the first game of the second set, avoiding an embarrassing potential 'double bagel' 6-0 6-0 score.
The crowd on Rod Laver Arena, which had its roof closed due to heavy rain in Melbourne, however managed to almost open it in the sixth game with a decibel-rising roar of support for Radwanska when she broke Williams to level it at 3-3.
Williams, however, broke again in the ninth game and then served out with three aces to seal a match in which she belted 42 winners to Radwanska's four.
Radwanska, who had been bidding to reach her second grand slam final after Wimbledon in 2012, also heavily lost her only other semi-final appearance at Melbourne Park when she was beaten 6-1 6-2 by Dominika Cibulkova in 2014.
(Reporting by Greg Stutchbury; Editing by Amlan Chakraborty)