System innovation for sustainability requires innovation in corporate governance. Social, ecological, economic, territorial and governance dimensions of sustainability are explored and a set of sustainability principles are integrated into a governance maturity grid. This grid enables both the assessment and the improvement of current strategic and operational practices regarding sustainability. It has been implemented in two industrial companies. As a result, it promotes senior management's reflection on their current strategies regarding value creation systems, and supports them in the definition of their sustainable strategies and the means of achieving them. This study is designed for businesses and presents a tool under development to support organizational innovation for system sustainability.