The 16-year-old's debut smash Royals had been sitting at number three on Billboard's Top 100 chart.
It jumped past Katy Perry's Roar and Cyrus' Wrecking Ball to hit the number one spot today.
The achievement makes Lorde the youngest solo artist top the Hot 100 since Tiffany, whose song I Think We're Alone Now took over at number one on November 7, 1987, when she was 16 years and one month old.
Lorde turns 17 on November 16.
She is now in a small club of New Zealand artists to rise to the top of the US charts.
OMC is the only other Kiwi act to hit number one in the US, with their song How Bizarre rising to the top of the chart in 1997.
Neil Finn's Don't Dream It's Over had a top chart placing of number two, while Kimbra was a guest vocalist on Australian artist Gotye's number one hit Somebody That I Used To Know last year.
According to Billboard, Royals had a 22 per cent lift in popularity to 128 million in all-format audience.
The ascent of Royals had been stunning, the website said.
Its success was driven by a 22% lift in its radio play, alongside continuing chart-topping digital sales figures of 294,000 downloads sold in the last week, Billboard said.
Royals also set the mark for the longest atop the Alternative Songs chart by a lead female artist - taking over from Alanis Morissette's You Oughta Know.
Meanwhile, Lorde's first album, Pure Heroine, is getting rave reviews in the US.
Billboard concluded the album would usher in the "age of Lorde", in a track-by-track review of its 10 songs.
Reviewer Jason Lipshutz said Pure Heroine mixed the "shadowy sonics" of Massive Attack and the XX with an intuitive pop sensibility.
"September has been a profoundly great month for new female vocalists in popular music, but Lorde is easily the most vocally striking and lyrically thought-provoking. Pure Heroine is honest and addictive. Welcome to the age of Lorde."
Grantland's reviewer Emily Yoshida said Pure Heroine was the work of a "future superstar.
"It just so happens that Pure Heroine, as its title cheekily implies, is wall-to-wall pop pleasure and very possibly the best album of the year."
