Katie Taylor saw off Amanda Serrano after 10 tough rounds to cement her status as the best in the world.
Boxing's pound-for-pound queen beat the Puerto Rican in New York to take her place in the list of the sport's immortals.
The pair put on a fight for the ages at a packed-out Madison Square Garden with Taylor's undisputed lightweight titles, and her unbeaten record, on the line.
And it was Taylor who won 'the biggest women's fight of all time' via split decision, with scores of 96-94 Serrano, 97-93 Taylor and 96-93 Taylor.
Both fighters went for it in the final two minutes but it was Taylor who ended the night with her hand raised.
After the fight Taylor said: "I knew I had to dig deep in this fight. I knew going into this I had to go to the trenches.
"Amanda Serrano is a phenomenal fighter. What a night. The biggest fight in female boxing history.
"I'm just grateful to be in this position really. What a night. What a fight."
Katie Taylor beat Amanda Serrano by split decision at Madison Square Garden
A true champion in every sense of the word.
Serrano meanwhile was ever gracious in defeat as she congratulated her opponent on her latest victory.
She added: "We put on a hell of a show. Katie is a great champion. She's undefeated and undisputed.
"I'm truly honoured to share the ring [with her].
"Women can sell, women can fight and women can put on a hell of a show."
Katie Taylor and Amanda Serrano congratulate each other on a historic night for women's boxing
Promoter Eddie Hearn was almost speechless as he took stock of what was a historic night for women's boxing.
Hearn told DAZN: "It was an amazing fight. It was a thrilling fight.
"I've said before, the way that women's boxing has longevity and sustainability is through equality.
"And tonight, forget male or female, you just saw one of the greatest fights in the history of Madison Square Garden.
"Amazing. I'm so proud of Katie Taylor. The greatest Irish athlete of all time in my opinion.
Katie Taylor had to dig deep to beat Amanda Serrano
"She's such a humble individual, such a great role model, such a great ambassador.
"Thank you to everyone for supporting this fight.
"Thank you to everyone from Puerto Rico and thank you to everyone from Ireland for coming out and supporting this incredible fighter in Katie Taylor."
However, it seems not everyone felt the same way, as Jake Paul thought Serrano had done enough to deserve the victory.
Amid a chorus of boos, he said: "It was a draw at best. We thought we won. We thought Amanda won.
"Amanda performed amazing, the performance of a lifetime. That was Arturo Gatti vs Micky Ward. That was incredible.
"Both women fought their hearts out - it was a historic moment.
"The crowd's booing but everyone's a winner here tonight.
"Kudos to Katie Taylor, what she's done for women's boxing, and kudos to Amanda Serrano.
"You've got to give credit where credit's due.
"Let's run it back, like Eddie said, September, October.
"The second fight just got a whole lot bigger."