Yes, you need an invitation letter to apply for a Germany Business Visa. A Germany Business Visa application requires an invitation letter from a German company or business partner. The invitation letter should detail the purpose of the visit, the dates of the visit, and the relationship between the applicant and the inviting company.
This letter helps establish the legitimacy of the business activities and supports the visa application. For entrepreneurs, a formal business plan may also be required in place of or in addition to an invitation letter.