He let slip news of his departure on his official website following a question from a fan asking what he wanted to say to critics of his solo performances during the Take That live shows.
"I must say I am aware that there is a perception in certain quarters and I'm enjoying throwing that perception down people's throats when I jump through the wall in L.M.E.Y (Let Me Entertain You)...I've never felt more on my game ..and it's thanks in part to the nay sayers....they have put a fire in my belly and in turn a smile on my face," he wrote on his blog.
"I'm blessed to have them... and when the tickets go on sale for my next tour I think we'll see what 'dwindling' looks like
" The group has recently been reunited with Williams after he famously fell out with band mate Gary Barlow at the peak of their fame almost 15 years ago.
The news that Take That were back with their original line-up sparked unprecedented demand for tickets to their huge UK tour and their latest album as a five-piece, ‘Progress', was the biggest-selling album of last year in the UK.
However, the 37 year-old singer has been getting a lot of stick for his 40 minute solo sections during the live shows.
One fan, gercia82, wrote on YouTube that Gary Barlow, Mark Owen, Jason Orange and Howard Donald were "better" without the singer while another user wrote: "OMG.. Robbie's performance was terrifying"