Keys opponent in Saturday’s final will be world number 83 Sloane Stephens, who beat ninth seed Venus Williams 6-1 0-6 7-5 in an earlier roller-coaster clash.
It will be the first time two American women have played for the title since 2002 when Venus lost 6-4 6-3 to her younger sister Serena Williams.
”I feels amazing, these are moments growing up you dream about,“ said Keys. ”It was one of those days where I came out and I was in a zone and forced myself to stay there.
”I had to rise to the occasion and I‘m just happy to be in the final.
“Sloane is a new person right now, I think she is loving being out on the court again and she’s obviously playing really well.”
The final shapes up as an intriguing and unexpected one featuring two players who missed the start of the year as they recovered from injuries.
Keys, who was absent from the first two months recovering from wrist surgery, delivered an old fashion thrashing as she needed just 66 minutes to beat Vandeweghe, who also lost in the Australian Open semi-finals.
Keys never faced a break point and committed just nine unforced errors while firing 25 winners.
“She was playing a great first set,” said emotional Vandeweghe, breaking into tears during her post-match media conference.
”I thought at some point she might start running a little bit colder than what she was doing. I mean, it’s really not over until the last point.
“I was fighting as hard as I could for as long as I could, but she stayed hot the whole time.”
Keys came out swinging against the fellow power-hitter and broke Vandeweghe twice as she stormed into a 5-0 in a one-sided opening set that took only 23 minutes.
Keys continued to hammer away in the second set and the 22-year-old broke in the third game to ensure her momentum continued.
The only alarming moment came when Keys called for a medical time out while leading 6-1 4-1 and she walked off the Arthur Ashe Stadium court for treatment.
The 15th seed returned with her right thigh heavily taped but it had no affect on her dominance as she held serve and finished off a shell-shocked Vandeweghe in her next service game with an ace on the first match point.
“I definitely was starting to feel it and I was afraid if I went too far into a corner then something more serious could happen so I felt I needed to get it worked on sooner rather than later,” said Keys.
“I feel great right now, I don’t think I could feel better than I do now.”