What is the role of Knowledge Management Systems (KMS) for a firm's innovativeness and absorptive capacity (ACAP)? Research shows that a firm's capacity to acquire and utilise relevant knowledge, i.e., its absorptive capacity, is decisive for innovation success. We develop a theoretical model that links the availability and usage of KMS with a firm's ACAP and its organisational knowledge to explain its contribution for a firm's innovation success. Using data from 222 manufacturing firms, we can show that the availability of a KMS in a firm affects its innovation success by contributing to its ACAP. Looking at the impact of different knowledge types on innovativeness, the results show that only technological knowledge is a substantial determinant of innovation success but not market knowledge.