The high street giant took to Facebook to share one of its spookiest – yet healthiest – treats.
But shoppers questioned whether the new item was some sort of an "April Fool's joke", reports Liverpool Echo.
Writing on social media, Marks and Spencer said: "These are not just any apples. These are ghoulishly good M&S red-fleshed apples.
"Bite into the skin of these healthy Halloween treats to reveal the bright-red flesh hidden inside. In stores now."
The image was shared with the post which shows the apples cut in half to reveal the bright red insides.
Since sharing the post on Monday, it received more than 2,100 likes and 1,000 comments.
While some were excited to try the apples, others were questioning if it was real.
One said: "If it wasn't October I would think this was a April Fool?!"
Another added: "Are these a different apple or are they just pumped with food colouring?"
M&S confirmed there was no food colouring inside the fruit and instead it was a "different variety of apple with red flesh".
And those who picked up the apples were very impressed with the taste.
A Facebook user said: "Bought some today in M&S. Just going to put them on here but you beat me to it. They are lovely."
Another added: "These look amazing! Can't wait to try them, my children will love them."
Meanwhile, one shopper asked if the apples were available in other stores.
The customer said: "Are these available through Ocado?"
Sadly, Marks and Spencer replied: "No I'm afraid not."
Head to your local Marks and Spencer now if you're brave enough to try these new apples!