Patrick hit the mark in the days leading up to Sunday's season-opening Daytona 500.
"It just shows what incredible and loyal fans I have," she told The Associated Press before the race. "It's pretty humbling that 1 million people are curious about what I have to say and what I'm doing. I really can't thank everyone enough for their passion and interest."
Although Patrick receives harsh criticism from die-hard NASCAR fans who accuse her of not having earned her ride in the Sprint Cup Series, she's enormously popular among casual sports fans and her loyal supporters.
She thanked longtime personal sponsor TISSOT for getting her started on Twitter, and GoDaddy, her NASCAR sponsor, for allowing her to be "organic, real and fun" while using social media.
The 1 million mark easily tops all NASCAR drivers. Next highest is six-time champion Jimmie Johnson's 530,000 followers. Juan Pablo Montoya leads all IndyCar drivers with just under 800,000. Patrick's boyfriend, fellow NASCAR driver Ricky Stenhouse Jr., has 126,000 followers.
Topping the 1 million mark ranks Patrick among the top female athletes. She's got more followers than Lindsey Vonn, Maria Sharapova, Mia Hamm and Anna Kournikova.
Those she still trails? Serena Williams' 4 million followers and U.S. soccer player Alex Morgan's 1.3 million.