Yeah okay, so not entirely paper.
Dr. Henrike Lähnemann, chair of German Studies at Newcastle University, has delivered a series of lectures looking at the use of paper in textiles. The items in question are late 15th century German dresses that once clothed religious statues. The Bodleian Library has published a short blog post about it here.
Paper has been documented as used in other pieces of clothing, too, but since until recently I’ve only studied 18th century clothing in depth, I’ve never noticed it used during another century. I’ve seen newsprint used in a banyan cap and some wallets, and paper or cardboard used in stays. I used two types of paper when I sewed myself an 18th century wallet, and it’s held up really well.
So why not? Paper isn’t too washable in the soap-and-water sense, but it was a cheap and available material, and works well as a light stiffener. Apparently, people figured that over 500 years ago, at least. Have you seen paper used in clothing from this time, or earlier? Comment below!