Abstract: Our study objective is to quantify the present and historical contribution of small-scale fisheries to national economies. We focus on the small-scale fishing sector in Sabah, Malaysia, and use a previously reconstructed time series of Sabah’s small-scale catches as the basis for estimating the economic value of these fisheries. Our findings suggest that since the early 1990s, small-scale fish catches in Sabah may have been undervalued by up to 225%. Presently, small-scale fisheries may be supporting up to an additional 3.5% of Sabah’s population. Further, accounting for the economic impact of unaccounted small-scale fisheries value could have potentially tripled the reported contribution that commercial and small-scale fisheries combined made to GDP in 2009. Overall, our results show that the socio-economic contribution of small-scale fisheries to Sabah society have been substantially undervalued or even unaccounted for historically and in present fisheries statistics. This undervaluation also implies that fishing pressure on Sabah’s inshore marine resources is probably a lot higher than presently perceived, raising concerns about the long-term sustainability of these fisheries resources, and the capacity for Sabah’s inshore fisheries to support coastal livelihoods into the future. Our study strongly suggests the need for more encompassing fisheries monitoring and data collection methods which target the large population of small-scale fishers whose catch is largely unreported.