I’d start by making the furniture less comfortable and less interesting to cats—without doing anything harmful. In an urban setting, stray cats are usually looking for three things: a soft place to rest, shelter, and an easy food source. If you remove those temptations around your outdoor furniture, you solve most of the problem.
First, cover or store what you can. Cushions, throw blankets, and soft seat pads are basically cat magnets. Bring them inside after you use them, or use a fitted outdoor furniture cover that stays on when the furniture is not in use. A cover does two things: it stops cat hair and paw prints from getting into the fabric, and it makes the surface less cozy. If a cover isn’t practical, at least flip cushions up on edge or store them in a deck box.
Next, make the surface unpleasant to land on. Cats like stable, quiet spots. A plastic carpet runner placed upside down—spiky side up—can work on seats or armrests, but only if it’s secure and won’t hurt anyone. Double-sided pet-safe tape can also discourage jumping onto rails or table edges. Some people use motion-activated sprinklers or air blasters near the furniture; these are humane and often very effective because cats hate sudden surprises. Just aim them so they won’t soak you, your neighbors, or delivery people.
Scent deterrents can help, but use them carefully. Cats tend to dislike citrus, lavender, and some strong herbal smells, but essential oils can be toxic to cats and other animals, so I would avoid spraying oils directly on furniture or in enclosed areas. Safer options include citrus peels placed in a shallow dish nearby, or commercial cat-repellent granules designed for outdoor use and applied according to the label. Reapply after rain, and don’t rely on scent alone—it’s usually a backup, not a full solution.
Urban cats also need to be kept away from food and trash. Secure garbage bags in bins with tight lids, don’t leave pet food outside, and ask neighbors not to feed strays near your patio or balcony. If someone in the building is putting food out, the cats will keep returning no matter what you do to the furniture. It’s worth having a polite conversation or contacting your building manager if needed.
Physical boundaries can be useful too. If your outdoor space is a balcony or stoop, check for gaps and easy jump-up points. Cats are excellent climbers, so barriers need to be tall or angled, but simple things like keeping furniture away from railings can reduce access. For ground-level patios, a low decorative screen or planter row can make the area less appealing.
Finally, be consistent. Cats are creatures of habit, and a deterrent that appears for one night and disappears won’t teach them much. Combine two or three methods—covering the furniture, using a motion deterrent, and removing food sources—and give it a couple of weeks. And please skip mothballs, poison, glue traps, and anything that could injure a cat. If there’s a neighborhood stray problem, humane TNR groups or local animal services may be able to help. The goal isn’t to punish the cats; it’s simply to make your furniture the least inviting spot on the block.