"To be honest, I'm a little bit shell-shocked," Cheryl told Radio 1's Jameela Jamil, who revealed the news.
Cheryl Fernandez-Versini has made chart history with her single I Don't Care
The star then thanked her "supporters and the fans that have done everything they could to get it here".
Shortly after the announcement was made, Cheryl took to Twitter. "So it is official. Today you got me my 5th no 1 solo single!!" she wrote. "You will stop at nothing & we did it!! WE MADE HISTORY!!!"
She added, "Thank you to all of you from the bottom of my heart for all of your support and congrats but this one is all YOURS!!!! #havingamoment."
Cheryl has previously topped the chart with Fight For This Love (2009), Promise This (2010), Call My Name (2012) and Crazy Stupid Love (2014). She also scored four number ones with her former band Girls Aloud between 2002 and 2008.
Cheryl Fernandez-Versini returned to the X Factor judging panel this year
The 31-year-old can now set her sights on the record held by Madonna, who has had 13 UK number ones, and Rihanna, who has eight.
This year has proved to be particularly special for Cheryl; as well as setting new records with her music, the star is enjoying her place back on The X Factor panel, and is happy being a newlywed with Jean-Bernard Fernandez-Versini.
The only downside to married life, it seems, is people failing to use her new name. Cheryl officially changed her name from Cole when she married Jean-Bernard in a secret wedding ceremony this summer.
"People are so ignorant about it, they just start calling us Cheryl. But I'll take that, whatever," she told Marie Claire.