Background: Despite growing interest in sustainable employability (SE), studies on the effectiveness of interventions aimed at employees’ SE are scarce. In this review, SE is defined by four core components: health, productivity, valuable work, and long-term perspective. The aim of this review is to summarize the effectiveness of employer-initiated SE interventions and to analyze whether their content and outcome measures addressed these SE components. Methods: A systematic search was performed in six databases for the period January 1997 to June 2018. The methodological quality of each included study was assessed. A customized form was used to extract data and categorize interventions according to SE components. Results: The initial search identified 596 articles and 7 studies were included. Methodological quality ranged from moderate to weak. All interventions addressed the components ‘health’ and ‘valuable work’. Positive effects were found for ‘valuable work’ outcomes. Conclusions: The quality of evidence was moderate to weak. The ‘valuable work’ component appeared essential for the effectiveness of SE interventions. Higher-quality evaluation studies are needed, as are interventions that effectively integrate all SE core components in their content.