The 18-year-old beat fourth seed Mayar Sherif 6-1 6-4 to qualify for the Flushing Meadows main draw.
Raducanu shot to fame by reaching Wimbledon’s fourth round in July, in a stunning first grand slam showing.
The fast-rising talent backed that up by reaching the final of the WTA Challenger event in Chicago last week.
And now Raducanu has fought through to the US Open first round proper.
Raducanu had kick-started her US Open qualifying bid by dispatching Holland’s Bibiane Schoofs 6-1 6-2, then ousted Georgia’s Mariam Bolkvadze 6-3 7-5 to reach the final round.
Another impressive victory has now allowed Raducanu to chalk off another milestone in her fledgling career.
Britain’s Katie Boulter also progressed with a 7-5 2-6 6-4 victory over Kristina Kucova.
Boulter delivered 10 aces as her serve proved the difference in a marathon match lasting two hours and 32 minutes.