With more than 200 scientists and engineers involved, the design and manufacture of the 4MOST instrument, a secondgeneration spectroscopic instrument built for ESO's 4.1-metre VISTA telescope, is a challenge requiring the implementation of an efficient quality assurance strategy during each project phase (i.e., design, manufacture, test, installation, and operation), and including the maintenance. This paper introduces the 4MOST product assurance approach used by the project to make sure that 4MOST will comply with all necessary quality and safety requirements over the whole instrument’s lifetime of 15 years. For quality assurance, the guiding principles are mainly given by the ISO 10007:2017 and ISO 9001:2015 quality management standards. Related to safety, 4MOST design and manufacture complies not only with the essential safety requirements from the European Union New Approach Directives (CE Marking Directives), but also with the additional requirements coming from the ESO Safety Policy, issued by the ESO Management for ESO-wide application. The implementation of the 4MOST project’s Quality Assurance and Configuration Management is described in detail in the paper.