During his appearance on Thursday's show, the money saving expert, 48, revealed to hosts Adil Ray and Charlotte Hawkins that he was "struggling" with the busy schedule, which included the weekly GMB segment.
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"My time is running out, this is actually my last ever Deals Of The Week because of my new show coming on every week in September, I am not going to do them anymore," he announced. "I hope to still pop on Good Morning Britain, it's been a wonderful 15-odd years on ITV daytime.
He added: "I am going to have a bit of a break for the summer, so I just want to say thank you all for watching… I will see you in September, I'm not leaving properly, but this is my main, every week slot going, because I can't cope with doing it all at once."
The money saving expert is leaving GMB
After sharing his news, Charlotte said: "Thank you Martin, because I know that you've made a big difference to lots of people who hang out for your tips. So thank you so much for that and enjoy your break in that case."
Martin then took to Twitter to post a heartfelt message, saying: "After 17ish years on ITV breakfast that was my last Deals of the Week. With @itvMLshow going live weekly every Thursday eve from September, for min six months, I need focus on that (I'll do some Deals there too).
"Thanks for watching these years and huge thanks to @gmb and it's a great team for everything." He then joked: "Ok now debating with myself whether I started on 2003 or 2005. Either way it's a long time."
GMB fans rushed to share their devastation, with one suggesting: "You can still record some Martin and they can show it mornings get people aware of what's need to do?" To which, Martin replied: "It's not the filming that's the work, it's the content. The five minutes on screen take hours of background research work. And I'll be doing those for my evening show."
A second viewer said: "Oh nooo what am I going to do without @MartinSLewis on @GMB anymore? Hope to see you pop up on there from time to time and thank you for all the advice you have shared with the nation over the years. #gmb."
Some fans were quick to congratulate him as one remarked: "You are the nation favourite and have helped so many. I wish you every success with the show and I’m sure with many more shows to come. Thank you Martin x." Another said: "Thanks for being one of life's good guys, you've helped so many."