Worker guidance systems are digital assistance systems in production, which provide work‐related information and, thus, guide employees through production processes. This article describes the user‐centered development of such a worker guidance system for a flexible production line in a metrology company. Usage context analysis and requirements analysis illustrate the need for a simple and independent system that can be used voluntarily by employees. After two iterations of the human‐centered design process, an interactive software prototype was created and implemented on a tablet personal computer. In this prototype, all essential process and assembly information in the flexible production line is available to the employees in the form of text descriptions and pictures as step‐by‐step instructions, which can be selected via two‐step navigation. The final evaluation was conducted as a user study with N = 10 assembly workers in the flexible production line under realistic conditions and was also intended to find out at which level of detail the information should be displayed in the system. The system scored well on the system usability scale (between 65.8 and 70.8) and concerning acceptance. Using the worker guidance system, no assembly faults occurred during the user study. Due to the significantly shorter assembly time, but no further significant differences, it was decided to set up the less detailed assembly information as a standard in the system. However, employees can call up more detailed information, if necessary. This system will be used by the company in the future.