The Angels singer has repeatedly made the joke as part of his concert routine over the years, but the tall tale has never sat well with Mel B, who insists she never slept with Robbie.
The two old pals were able to catch up on Sunday (20Nov16), when Robbie appeared on X Factor Australia, on which Mel B is a judge, and she reveals he used the opportunity to say sorry.
"He actually publicly apologised to me for all that mess... saying he had apparently gotten it on with all five Spice Girls," Mel shared with Australian radio hosts Kyle and Jackie O on Monday (21Nov16).
"He wishes!" she laughed, adding, "I was the one he never did."
Revealing why she never got intimate with the former Take That star, she said, "He's a friend of mine... Yuck! He had been with my friends - I don't want sloppy seconds."
Robbie's cheeky behaviour during his pop heyday hit headlines again over the summer (Jul16) as his wife Ayda Field appeared to confirm part of his concert comment is actually true, suggesting he had previously slept with three of the five Wannabe hitmakers - Geri Horner, Emma Bunton, and Melanie Chisholm.
Robbie himself has never named his Spice Girls conquests, but during an appearance on Nova FM's Fitzy and Wippa show in October (16), he admitted his joke had "got out of hand".
"You know Back For Good, the Take That song? I used to sing that on stage," Robbie explained. "I still do. On one particular tour... I introduced it by saying, 'I am very fortunate to have been in Take That and four out of five of the Spice Girls.' That was my intro to the song and it was a joke and the joke went too far."
Issuing an apology to the ladies and their families, he added, "I would like to apologise to all the Spice Girls involved and their husbands and boyfriends. I know a few husbands and boyfriends weren't too happy with the joke."