Honestly, I’d treat this as a layers problem: make the bench hard to move, hard to strip, and easy to trace. Start by anchoring it properly. If you’re on concrete, use expansion anchors or chemical anchor bolts through the bench feet. On soil, sink a concrete footing or use heavy-duty ground spikes designed for outdoor furniture. The goal is that two people cannot simply lift it and walk away.
Next, change the hardware. Standard bolts are too easy to remove with a wrench. Use tamper-resistant or security screws—Torx pin, tri-groove, or one-way screws—and add blue threadlocker so they can’t be quietly loosened. If the bench folds or is designed to be moved, add a hardened steel cable lock or chain through the frame and around a fixed object like a light pole, fence post, or bollard. It won’t stop someone with an angle grinder, but it will stop an opportunistic grab.
You can also make the bench traceable and identifiable. Hide a weatherproof GPS tracker or a small smart tag inside the frame tubing, under the seat, or behind a maintenance cover. At the same time, engrave or stencil the name of the park, building, or property ID in a visible spot and also in a hidden spot. Marked items are harder to resell and easier for police to identify. Check local rules before drilling into public property or adding a tracking tag, since some spaces have restrictions on modifications.
Placement matters more than people expect. Put the bench where it is visible from active areas, under lighting, and preferably covered by a security camera. Thieves dislike working in plain view. You can also arrange planters, bollards, or railings around it to make a quick carry path awkward. If the bench only needs to be out during certain hours, have staff or volunteers bring it inside at closing time and lock it in a storage room or cage.
Finally, keep records. Take photos of the bench, note any serial or asset numbers, and register it with a local police or property database if your area has one. A cheap “smile, you’re on camera” sign nearby can also help. You won’t make theft impossible, but you can make it enough of a hassle that most people will target something easier.