This was an opportunity missed for the Polish fifth seed, who had sent two-time defending Australian Open champion Victoria Azarenka packing.
Radwanska was flat and slow against Slovakian 20th seed Cibulkova, losing 6-1 6-2 in one hour and 10 minutes.
The 2012 Wimbledon runner-up had spent two hours and 24 minutes longer on court leading into the semi-final.
That – and how tough the win over Azarenka was – made it too big a task for Radwanska.
"Well, I think I feel like in slow motion today," she said.
"I had a couple tough matches, especially yesterday. Yeah, well, I think I was not fresh enough."
Radwanska praised Cibulkova for what has been a strong tournament by the Slovak, who has dropped just one set on her way to the decider.
"Well, definitely she did play well whole tournament, but I think I spend twice more hours than her on court. I think that's it," she said.
Cibulkova said she found it tough to stay in the moment during the second set, when her maiden grand slam final appearance looked all but certain.
"I was just trying to focus on my game. Since the first point till the last point of the match I was just trying to do the right things," she said.
"I wanted to enjoy. Of course it was not easy when I was up in the second set. The thought started to come that I could win, the result and everything.
"I have to say, I was 100 per cent ready for it and I was just doing what I had to do.
That's why I won.
"It wasn't easy, because against her you have to earn every point, you have to do the right thing, and that's what I did."