The new world No 1 overtakes the previous record she shared with Steffi Graf. Only Margaret Court, who won 13 of her 24 Majors before the Open era started in 1969, has ever won more.
Serena beat Venus 6-4 6-4 in 82 minutes to win her seventh Australian Open title without dropping a set.
At the age of 35, she also breaks her own record for the oldest female Grand Slam champion in the Open era.
After falling to the court in the Rod Laver Arena after the final point, Serena was embraced at the net by her sister.
Serena said: “I would really like to take this moment to congratulate Venus, she is an amazing person. There is no way I would be at 23 without her.
There is no way I would be at one without her.
“She is my inspiration, she is the only reason I am standing here today and the only reason that the Williams sisters exist.
“Thank you Venus for inspiring me to be the best player that I could be and inspire me to work hard every time you won this week I felt like I got a win too.”