The DJ and producer, who is seen in the studio with Harding in the video for new single '2Gether', insisted that the Girls Aloud star - known for her partying - is a "very chilled out person".
"We met in Ibiza. One of her friends is good friends with me and put us in touch," Sanchez told Digital Spy.
"She asked if she could meet me with her boyfriend while I was DJ-ing out there last year. We hit it off and discussed laying some music down in the studio."
He added: "She has a reputation as a party animal, but she was actually quite subdued and a very chilled-out person."
The 'Another Chance' hitmaker recently revealed that he had produced a track for Harding with McFly singer Danny Jones.
> Click here to read the full interview with Roger Sanchez