Not always – and it’s worth being honest about that. For a straightforward store with a standard theme and a modest catalogue, you can set WooCommerce up yourself. It’s designed to be usable without writing code, and plenty of small stores run perfectly well DIY.
You genuinely need a developer when:
you want custom functionality or integrations (ERP, subscriptions, unusual shipping/tax); you need real performance and conversion work rather than default settings; or the store is important enough that slowness and downtime cost you real money. At that point, expert help pays for itself.
The honest rule: match the help to the stakes. A hobby store doesn’t need us; a store doing serious revenue on a slow, fragile setup does. If you’re not sure which you are, a diagnostic that measures where you’re losing sales will tell you. More: what a WooCommerce developer does · is WooCommerce good for beginners?