The former Take That singer dropped his holiday album, "The Christmas Present", on Friday, November 22, and, in a chat with Britain's Heart radio, he revealed the "Toxic" hitmaker was originally set to feature on the LP.
Explaining that his favourite festive tune is The Pogues' hit with the late Kirsty MacColl, the star revealed: "I asked Britney Spears to duet with me... She said no. What a lovely story".
When host Jamie Theakston asked, "What did you do? Did you ring her or did she just not text you back, how did that work?" Robbie explained: "She's not working right now. She's having a rest".
He teased: "Maybe it'll happen in the future".
The track was eventually axed from the recording altogether.
Meanwhile, Britney is on an "indefinite hiatus" from work, after scrapping her planned Britney: Domination Las Vegas residency while her father, James Spears, battled health issues.
Since then, the star has been locked in an ongoing court battle relating to her father's conservatorship over her, after she was admitted to a mental health treatment facility earlier in the year.