This paper examines the role of customer-affiliated outside directors on suppliers in reducing risk arising from customer concentration. Using a sample of US suppliers over the 2001–2016 period, we find that a positive relationship between customer concentration and supplier firm risk is weakened with the presence of customers' representatives at suppliers' board. We further show that supplier firms with customer-affiliated outside directors are more likely to have less conservative financial policies. Our results suggest that customers' board membership at suppliers helps mitigate the customer concentration risk due to the tightened supplier–customer relationship and reduced information asymmetry.