Furious mother Emily Bowie told local newspaper The Evening Times that staff at the Braehead branch in Glasgow turned her daughter away after she explained she had the disorder.
Emily told the paper: "Everything had been going smoothly, my daughter was really excited at getting in to play but when I mentioned she was mildly autistic their attitude completely changed and they said she couldn’t get in due to her autism.
"I was really shocked - I thought things like this were from the dark ages."
Nick Ward, Director at the National Autistic Society Scotland said: “We have not been contacted about this but if what has been reported is accurate then it is sadly a story we hear all too often.
“Our research found 44 percent of autistic people and their families sometimes do not go out because they are worried how people will react to their autism - but we also know that small adjustments, such as staff training, can make a big difference.
“We want a society that works for autistic people and their families – this means creating an inclusive and accessible environment so everyone can enjoy the same experiences.
"No autistic person should be treated differently or turned away simply because they are autistic.
An IKEA spokeswoman said, “We want to make sure our stores are accessible to as many people as possible and we are aware that we recently disappointed a customer wanting to use our Småland crèche.
"For children with additional needs, our policy is to offer one to one care on their first visit and then based on this, assess the needs for future sessions.
"On this occasion, our crèche had reached the maximum number of children to allocated staff and we were therefore unable to provide the necessary care required.
"We have since apologised for any inconvenience caused and have been in contact with the customer to understand how we can best support their child’s needs on their next visit.”