—In a Wireless Local Area Network (WLAN), the Access Point (AP) selection of a client heavily influences the performance of its own and others. Through theoretical analysis, we reveal that previously proposed association protocols are not effective in maximizing the minimal throughput among all clients. Accordingly, we propose an online AP association strategy that not only achieves a minimal throughput (among all clients) that is provably close to the optimum, but also works effectively in practice with a reasonable computational overhead. The association protocol applying this strategy is implemented on the commercial hardware and compatible with legacy APs without any modification. We demonstrate its feasibility and performance through real experiments.