In short, yes—but it is not usually a simple case of drilling a plaque onto any bench. Most cities, parks departments, campuses, and other public-space managers allow memorial or dedication plaques on urban outdoor furniture only through an approved commemorative or donation program. The first step is to confirm who owns the furniture and what their policy says. A bench in a public park may belong to the parks department, a business improvement district, a university, or a private landlord, and each may have different rules.
Direct engraving works best on timber, stone, or cast-metal components that can be refinished or replaced. For steel, aluminum, or composite furniture, an attached plaque is often more practical. Bronze, stainless steel, and anodized aluminum are common choices because they handle weather and UV exposure well. Lettering should be recessed or engraved rather than simply printed, and fixings should be tamper-resistant without creating sharp edges or trip hazards.
Design and safety matter too. Plaques should not block seating clearances, interfere with accessibility, or cover structural joints. Cities often specify size, wording, font, finish, and mounting location, and they may reject anything that looks like advertising or creates maintenance problems. On heritage furniture, reversible mounting is usually preferred.
So for a real project, I would advise contacting the furniture owner early, asking for their memorial plaque guidelines, getting written approval for the text and dimensions, and using a fabricator who understands outdoor fixings and corrosion. If that process is followed, engraved or plaque-mounted memorials can be a thoughtful and durable part of urban outdoor furniture.