In today’s ever-changing market, startups that can effectively respond to environmental changes and can manage unpredictable events will face intense competition. Human resources play a special role in promoting the competitiveness of startups. This study investigated the effect of high-performance work systems (HPWSs) on the competitiveness of startups through the mediating role of innovation capability maturity. The statistical population of the study consisted of Iranian startups based in Isfahan Province. Data were collected using a standard questionnaire, and the structural equation method was used to data analysis. The results showed that high-performance work systems have a positive and significant impact on the competitiveness of the studied startups through the mediating role of innovation capability maturity and about 47% of the total effect of the high-performance work system on competitiveness of them is explained indirectly by the mediating variable of innovation capability maturity.