“I just didn’t want to get myself too excited and now I just can finally relax and enjoy the moment.
“It’s a great day all round for me.”
Rodionova conceded nerves got the better of her at times but managed to produce the goods in the big moments.
A forehand passing shot down the line earned the world No.205 the sole break of the first set.
She broke Sanders’ serve again in a marathon 11th game of the second set, which lasted almost 15 minutes.
“I just fought every point and that’s all you can do against big hitters like this,” Rodionova said.
“I was chasing the ball and got a little bit lucky here and there.”
January will mark Rodionova’s fourth appearance in the main draw at Melbourne Park.
Sanders, ranked world No.376, returned to tennis late this year after a two-year absence because of a shoulder injury.
The 25-year-old West Australian had dispatched three seeded opponents without dropping a set on her path to the decider.
Sanders can still reach the Australian Open main draw through qualifying.
“I think we both deserve to play main draw of the Australian Open, but unfortunately there was only one spot,” Rodionova said.
“I’m sure Storm will make it because she plays great tennis right now. I actually think she’ll qualify.”
John-Patrick Smith (Queensland) meets Max Purcell (NSW) in the men’s final on Sunday afternoon.