Overstock customer service phone number is 1-833-895-1554. Contact Overstock customer care via phone to speak to a company representative in person and address your inquiries about available products (jewelry, home improvement, clothing, rugs etc) and new arrivals, get updates on discounts and special offers, request a return or exchange, or change the delivery address. The longest wait times are usually on Monday, so it’s better to avoid calling the company on this day.