In most cities, yes—you’ll usually need some form of permit or written approval before placing urban outdoor furniture on a public sidewalk. A public sidewalk is typically part of the public right-of-way, even if it sits directly outside your storefront, café, apartment building, or office. Benches, planters, tables, chairs, display items, and similar furniture can affect pedestrian access, accessibility, fire lanes, utility access, and sight lines, so local agencies usually want to review the placement before it goes in.
That said, the rules are not the same everywhere. Some cities use a simple encroachment or right-of-way permit. Others require a sidewalk café permit, outdoor dining approval, insurance, fees, and a maintenance plan. Small temporary items may be treated differently from permanent benches or large planters, and some areas may prohibit furniture entirely if the sidewalk is too narrow or if a clear pedestrian path cannot be maintained.
Your best next step is to contact your local public works, transportation, permitting, or business licensing office. Ask specifically about furniture on a public sidewalk, and be ready to share the location, dimensions, furniture type, anchoring method, and how much clear space will remain for pedestrians and wheelchair users. If you skip the permit, the city may ask you to remove the furniture, charge fines, or remove it for you. So before you buy or install anything, check the local rules and get approval in writing. This is general information, not legal advice, and local requirements can change.