Taylor earned the win with scorecards of 97-93, 94-96 and 96-93 and in doing so, extended her unbeaten record to 21-0.
There is much discussion about who the best female fighter is on the planet and often, Taylor, Serrano and Claressa Shields are the three in the discussion.
Now the 'Bray Bomber' has beat Serrano, the debate has gone down to two in Taylor and Shields.
America's Shields is a double Olympic champion and has won world titles in three weight divisions but according to analyst Andy Clarke, Taylor's recent win puts her above Shields.
"I used to have Claressa Shields as number one just because of the body of work and what she has achieved and all the titles she had won kind of thing but unfortunately she doesn't have the dance partners that Taylor's had," Clarke told Planet Sport.
"She has had fights people will remember for a very long time and Shields hasn't had that yet. She'll be kind of almost hoping she gets one of them against Savannah Marshall - that she wins but that it is one of those kind of fights because she needs one of them really.
"It was a brilliant fight and Katie Taylor has been absolutely incredible for 15 years," Clarke added about Taylor-Serrano. "The pressure she (Taylor) has been under to win every time she goes out there is absolutely absurd."
Stick to two minute rounds?
Another argument is the current system female fighters operate in. As it stands, they fight two, 10 minute rounds - something which has been questioned by the likes of Amanda Serrano.
Had her fight been three minutes per round, then she may have stopped Taylor in the fifth round having hurt her badly. However, due to the two minute rounds, it spared Taylor from the brink of defeat.
Clarke though is a huge fan of the current system although he would like an additional two rounds added moving forward.
"I just love these 2 x 10 minute rounds - I mean maybe they should be doing 12 x 2 minute rounds that would be the next step you would say. I understand people calling for three minute rounds.
"I think some people are doing it for the wrong reasons but the level of entertainment from these two minute rounds is absolutely tremendous. I've been ringside for most of Katie Taylor's fights and those two against Persoon, Natasha Jonas and then this one - they're classics, they're great fights.
"I personally don't want to see them step up and do three minute rounds because although everybody endlessly talks about equality in sport and in all areas, and I understand why and that's what everybody wants to achieve but men's and women's sport are different.
"Because men and women are different. If the difference is that women give us a different kind of fight by boxing over two minute rounds - this incredible fast tempo cramped into 24 minutes as opposed to the men which may be a little bit slower but with more knockouts, I'm fine with that as a kind of selling point - a USP then that could be the way to go.
"If people want three minute rounds just because people want to see someone get knocked out then what's that about? I understand why a lot of fighters might want three minute rounds because Serrano would have knocked Katie Taylor out in the third minute of that fifth round but maybe she wouldn't.
"Maybe she would have knocked her down and Serrano would have punched herself out in the remaining minute we don't know. People look at it and make all sort of assumptions," Clarke concluded.