So it was with baited breath that fans waited to see if he would join the quartet at a Children In Need charity concert.
And their prayers were answered – partially.
Take That opened the musical extravaganza – organised by Gary - at the Royal Albert Hall with a rendition of their hit single Greatest Day.
It was then the moment the audience had been waiting for as singer-songwriter Gary announced the 35-year-old singer on to the stage.
"What a perfect night for us to introduce an old friend," he said as the tearful musician appeared.
Overcome with emotion, he hugged his former band mates each in turn as he soaked up the limelight with Gary Barlow, newlywed Mark Owen, Howard Donald and Jason Orange once again.
Despite hopes that the five would reunite for a special performance of an old Take That number, the boys then left Robbie on stage to sing his solo singles Bodies and You Know Me.
Speaking after the show, the Stoke-on-Trent-born star said: "I was tearing up just before I came on and the lads were singing and knowing it was just about to happen and knowing what the reactions were going to be like, and then all my team were like 'Please don't cry.'"
"And I think we should have milked it for a lot longer than we actually did," Robbie added.
His sentiments were echoed by Gary himself who said: "Robbie was the icing on the cake for the whole gig. We wanted to stay on and do ten songs. It felt great having him back."
Clearly relations between all the boys are at a high – Robbie and Gary sang together with their arms around each other's shoulders as they joined all the evening's acts for a finale of Beatles classic Hey Jude, led by Paul McCartney.
So does that mean there is a Take That reunion is definitely on the cards?
"We'll save that for something special, whatever that is," teased Robbie, denying it would be at the next Brit awards.
"I'm not nervous anymore because we've seen each other…the bitterness and resentment has completely gone and I'm just left with four other lads that I just love to pieces."