Grand Rapids Chair Co. Sligh Furniture Bench Stool

Yes, it does look like a seat for a vanity set. This is the closest I could find to yours, a bit more detail in this one https://www.ebth.com/items/1815660-antique-sligh-vanity-with-seat
Here’s some info on the company. None of the labels are exactly like yours though I have seen other pieces with the same label. I’m not sure on the time period http://www.furniturecityhistory.org/company/3824/sligh-furniture-co I’d guess https://www.homefurnishingshalloffame.com/charles-r-sligh-sligh-furnitu… 1919 based on that one label or early 1920’s. I did read that their bedroom sets were made from the 1920’s - 1930’s. Here’s one from the 30’s https://www.harpgallery.com/shop/item27929.html
More detailed info https://www.homefurnishingshalloffame.com/charles-r-sligh-sligh-furnitu…
I don’t know the value of your chair but am sure it’d be worth more with the vanity.

Based on the images and the label your piece dates from the first quarter of the 20th century. Not much value for the vanity seat on it's own or even if it included the vanity, as furniture of this type was mass produced and not of great quality. comparable vanity seats and stools often sell for under $30.00 at auction and yard sales.