Raducanu – the lowest-ranked woman to reach a Major semi-final since Wimbledon 2018 – stunned No.17 seed Sakkari 6-1 6-4 in New York on Friday (AEST).
The 18-year-old will face fellow teenager Leylah Fernandez, 19, in Sunday's (AEST) decider at Flushing Meadows after powering past the Greek star, with Raducanu the first Brit to contest a championship match at the US Open since 1968 winner Virginia Wade.
It will be the eighth grand slam final between teenagers in the Open Era and first since the US Open in 1999, when Serena Williams beat Martina Hingis.
Raducanu, who impressed in making this year's Wimbledon fourth round, was the first British woman to reach the semi-final stage of the US Open singles since Jo Durie in 1983 but she was not overawed under the Arthur Ashe Stadium lights.
After fending off three break points against Sakkari in the opening game, Raducanu, who had only been broken five times entering the contest, broke for a 2-0 lead.
That set the tone for an incredible first set, which was ultimately decided on second serve as Raducanu blew away her experienced opponent.
Raducanu won 73 per cent of her second serves as she saved seven break points to thwart Sakkari, who only won four of her 13 second serves in comparison.
Sakkari – also looking to reach her first major final – tried to will herself on in the second set, however, the 26-year-old simply had no answers.
Raducanu did not face a break point in the second set as the world No.150 continued her fairytale run in the United States.