The first logical thing to do is sew a custom cover, but that can be expensive. If not, its still time consuming, and can be hard for some people, such as those without sewing skill. What is the next logical solution? Fortunately, I have come up with this idea. I've seen many kinds of clothing tops used as seat back covers on cars and trucks, usually unisex t-shirts, but also gender specific sizes, both pullover and zip up hoodies, polo and henley shirts, tank tops and other kinds of sleeveless tops, sweaters and sweatshirts, button up shirts, and in one case, a car had womens blouses as seat covers. This is done, of course, to protect the car seat but also add style and personality to the car. So why not do this with the office chair? with an office chair, the bottom seat part can also be covered due to the way it can be easily dismantled and the general way it's put together. It may be easier if the chair is just right out of box in pieces.
If your chair is assembled already you would need the tools to disassemble and reassemble it. Also, if you're like me and don't like to use old clothing, buy something new and cheap. In the photo, the t-shirt on the backrest was $5 on clearance.
Start by disassembling the chair if it's assembled. Then, take the backrest and seat and put them on a table either both if the table's big enough or one at a time. MAKE SURE THIS TABLE IS CLEAN. Start with the backrest first because all you do is slip on the top from the top of the back (the neck hole should be on top once assembled) with the front facing forward (the front of the top will be where you lean on, see pic for reference) using any seams to align it perfectly. Also, if you're using a zip up hoodie, button up shirt, or blouse, zip it all up/do all the buttons. If there are knobs on the back, no holes have to be made. If the armrest is integrated in the back however, the back can NOT be covered as this is meant to be removable for washing, changing out, and wearing if there is a reason. For the seat, it will be impossible to remove for washing, wearing, or changing, and holes will be made so it's best to use something old here. Take the top and slip it on the seat with the neck hole at the rear of the seat, and the front of the top will be where you sit on. Then, reassemble the chair. The screws should make holes in the fabric. It's your choice if you want to leave the excess bottom part of the top hanging or fold it and fasten with the screws while reassembling. At the end, manage the sleeves as with the backrest A pic of this will come later on.
Now the chair is protected from stains, dirty stuff, wear and tear, and will surely catch a lot of eyes. Post a pic in the comments if you did this! Also, a bonus if you used a pullover hoodie, putting a portion of a pool noodle or a similar soft foam cylinder in the pocket, and then putting the sleeves on it, you can have lumbar support.