No. Not well, and usually not at all.
A king comforter is roughly 102 inches wide. A queen duvet cover is roughly 88 to 90. You are trying to fit fourteen extra inches of loft into a fabric envelope that has no give in that direction. If you force it, one of three things happens: the closure won't fasten, the seams take strain they weren't sewn for, or the comforter compresses into a dense slab that sits high in the middle and flat at the edges.
People try this for a good reason. Either they own a king comforter from a previous bed, or they've read that sizing up gives a better drape. The second idea is correct. The execution isn't: you size up both pieces together, not one of them.
How much oversize is actually workable
Roughly:
- Up to 2 inches larger than the cover in each direction. Ideal, and what you want.
- 3 to 6 inches larger. It fits, it feels full, the closure is snug. Acceptable.
- More than 6 inches larger. Stop. The cover is under constant tension and you'll be repairing a seam within a year.
King into queen is about fourteen inches over. That's twice the outer limit.
What to do instead
If the goal is a fuller bed: buy a king cover to go with the king comforter and use both on the queen mattress. This is a legitimate, common setup, especially on a mattress 14 inches or taller. You get several extra inches of drape on each side, and the bed looks intentional rather than under-dressed. The only real cost is that the cover is a size up in price.
If the goal is to use up a comforter you already own: check whether it's actually a king. Comforter labels are as unreliable as cover labels. Measure it flat. If it comes in at 92 or 94 inches wide rather than 102, it may genuinely work in a large queen cover, since the 90" × 92" covers on the market have more room than the 88" × 88" ones.
If it really is 102 inches and you only have a queen cover: use it on the guest bed, use it as a spare layer folded at the foot of the bed, or keep it for winter and buy the matching cover later. Cramming it in isn't a compromise, it's a slow way to ruin two things.
The reverse case
A queen comforter in a king cover is the other question people ask, and it's a different failure. The cover won't be damaged, there's plenty of room. It just won't look right. About twelve inches of empty fabric hangs off each side and the corners collapse. The bed reads as deflated.
Undersize is more forgiving than oversize for the fabric, and less forgiving for the eye. Neither is a good outcome.
Before you order anything
Measure the comforter flat, in both directions, and compare it to the cover's listed dimensions in inches. Not to its size name. The labels won't tell you enough. Two products can both be "Queen" and differ by four inches, which is exactly why this question comes up as often as it does.
If you're starting fresh, our duvet sets list finished dimensions in inches, so you can check the fit before the box arrives rather than after.