The effects of solid-state fermentation of Flos Lonicerae japonicae (FLJ), in the presence of Monascus anka, on its polyphenolic content and antioxidative activities were investigated. The optimal fermentation conditions were found to be a substrate water content of 50%, an inoculum size of 10%, and a fermentation period of 9 d. The total polyphenolic content of the fermented FLJ was 36.00 mg GAE/g DM, which was 62.32% higher than that of the unfermented FLJ. The total flavonoid content was also higher (by 40.40%) at 70.49 mg RE/g DM. According to the HPLC results, chlorogenic acid (at 20.55 mg/g) was the most abundant component in the polyphenolic extract, and the caffeic acid content was 55.56% higher than that of the unfermented FLJ. The flavonoid content was also significantly increased in the fermented FLJ, with isoquercitrin and quercitrin reaching amounts of 1.65 mg/g and 0.24 mg/g, respectively, which were 12 and 18 times higher than those of the unfermented FLJ. The fermented FLJ also exhibited stronger antioxidative activities, with the ABTS+ radical- and DPPH radical-scavenging activities increased by 61.39% and 59.28%, respectively. Taken together, these results indicate that the solid-state fermentation of FLJ in the presence of M. anka can effectively increase the polyphenolic content and antioxidative activities of this Chinese herb.