Graduates require employability competences, such as flexibility and team working skills, to gain and maintain employment. Online learning platforms (OLPs) can provide students with resources for reflection, which is a key competence for employability. However, little is known about the design of OLPs meant to provide reflective practices that foster students' employability competences. This research study aims to identify design principles of OLPs providing reflective practices that foster the development of employability competences. Five design principles were derived from thematic analysis following two focus group interviews with students and educational experts in this qualitative study: (1) Embed the OLP in curricular and institutional activities that foster competence development; (2) Facilitate the analysis of students' current state regarding employability competences; (3) Provide recommendations and a repository with learning activities that help students to formulate goals and plan activities; (4) Facilitate the undertaking and recording of learning activities, supported by a blend of three forms of interaction (instructor-student; student-student or student-content); and (5) Foster reflection in and on action via opportunities for applying newly learned knowledge in different settings and reviewing activities via reflective journaling and knowledge sharing. This study is the first to conceptualise design principles for an OLP that is organised to provide reflective practices for the development of employability competences. The design principles were based on students' and teachers' experiences and are grounded in theory. They can inform future research as well as practitioners developing OLPs.