Although the use of English borrowings in Chinese is not uncommon, there are still few studies having explored the pragmatic dimension of these borrowings. Besides, few of the previous studies adopt an onomasiological approach to study borrowings. Thus, this study aims to investigate the pragmatic functions of English borrowings by comparing English borrowings with their native equivalents in line with the onomasiological approach. To this end, the study collects data from Weibo and divides the English borrowings occurring in the hot topics on Weibo into two types based on the existence of native equivalents, namely, catachrestic borrowings and non-catachrestic borrowings. It is revealed in the study that catachrestic borrowings provide a stereotypical interpretation of a concept that has not been lexicalized in Chinese and primarily serve the function of filling lexical gaps while non-catachrestic borrowings can create special pragmatic effects as marked choices in contrast to their native equivalents. While drawing the distinction between catachrestic and non-catachrestic borrowings helps shed light on their different functions, this study argues that the distinction is dynamic and context-dependent as the pragmatic functions of borrowings are conditioned by contexts and susceptible to change. By analyzing borrowings from the pragmatic dimension, this study not only demonstrates the importance of pragmatic functions in people’s adoption of borrowings but also confirms the applicability and effectiveness of an onomasiological approach to borrowing.