In the starting phase, despite incentives of government support policies and related entities' supports, startup companies face many difficulties in accessing external information and resources to innovate current business models. The role of management resources in building relationship networks to promote business model innovation (BMI) is a popular topic but has not been tested in transition markets and the context of Industry 4.0. This study was conducted by applying the Partial Least Squares method (PLS-SEM) to examine relationship networks and BMI of startup companies in Vietnam. The research results showed that relationship with government officials positively influences BMI's components; social relations positively affect value proposition innovation; relationship with business partners positively influences value creation innovation and value proposition innovation. Relationship network and BMI are essential for startup companies to respond to environmental changes. The research results also provide useful information for startup support organizations in connecting and consulting effective business models for startup companies.

A report of GEM (2018) stated that start-up firms with the total time doing business under 3.5 years have only 20.8% success rate. Among various reasons leading to their failure, not having an appropriate innovating business model is considered the major one. Thus, this research was conducted with the purpose of testing the influence of business model innovation on the business performance of start-up firms. This study applied PLS-SEM approach to process data collected from 150 Vietnamese start-up firms. It is confirmed based on the research findings that BMI’s three basic components have impacts with the same direction on the performance of start-up firms in their beginning period of doing business. The study results collected have presented practical contribution to the management level of each start-up firm in order to improve their effectiveness. On the other hand, suggestions are also proposed to assist other relating organizations in developing their abilities to support start-up activities. In addition, research limitations and directions for further researches are proposed.