Superannuation funds heavily outsource key fund functions to service providers who play a crucial role in superannuation fund operations and affecting Australians’ retirement savings. We examine the impact of related party service provider usage and trustee‐director affiliation on investment performance. We find that for‐profit funds significantly underperform when using related party service providers. The underperformance is more severe when the board is controlled by more affiliated trustee‐directors and belongs to a vertically integrated conglomerate group. Our results raise concerns about whether recent regulatory reforms increasing trustee‐directors’ duties effectively address the conflicts of interest inherent in related party service provider arrangements.