Uncertainty has been widely recognized as a primary barrier in online C2C transaction processes. This research explores the effectiveness of strategies typically employed to reduce uncertainty in C2C electronic commerce based upon the uncertainty reduction theory and Kelley’s attribution theory. We inspect the effects of the information from four information seeking strategies on online consumers’ perception of uncertainty when initially transacting with an unknown seller in an online marketplace in China; we also integrate the two most prominent contextual factors, information consistency and seller reputation, to explore their direct effects, as well as their interactive effects with information from the four strategies on uncertainty. An online survey is used to collect data from the three most prestigious online store marketplaces in China. The results specify the exact effects of these factors on uncertainty in different contextual conditions. Finally, the theoretical and practical implications of this research are discussed.