Background: Fuzi–Gancao herb couple is one of the commonly used herb couples involved in the traditional Chinese medicine formulations, with radix aconiti lateralis (Fuzi in Chinese) and radix glycyrrhizae (Gancao in Chinese) as a ratio of 1:1. Alkaloids and flavonoids were considered as the main active ingredients of Fuzi–Gancao herb couple. However, no analytical methods have been reported to quantitatively analyze these activity ingredients in Fuzi–Gancao herb couple simultaneously. Objective: To develop a simple, rapid, and sensitive UHPLC-MS/MS method for simultaneous quantitation of six alkaloid and three flavonoid compounds, namely, aconitine (AC), mesaconitine (MA), hypaconitine (HA), benzoylaconitine (BAC), benzoylmesaconitine (BMA), benzoylhypaconitine (BHA), liquiritin, isoliquiritin, and licochalcone A (LCA) in Fuzi–Gancao herb couple. Materials and Methods: The chromatographic separation was achieved using a reversed phase C18 column and a mobile phase consisted of water (0.1% formic acid in water, v/v) and acetonitrile. The detection was achieved in multiple reaction monitoring modes. The optimal mass transition ion pairs (m/z) for quantitation were 646.3/586.5 for AC, 632.4/572.5 for MA, 616.3/556.4 for HA, 604.5/572.5 for BAC, 590.4/540.4 for BMA, 574.1/542.5 for BHA, 419.4/257.1 for liquiritin, 419.4/257.1 for isoliquiritin, and 339.2/121.1 for LCA. Results: Good linearity was observed in validated concentration range for each analyte (r > 0.9992), and the intra- and inter-day precisions were <3.12% and 3.65%, respectively. The recovery ranged from 85.36% to 110.14%. Conclusions: The results demonstrated that the method developed was reliable, rapid, and specific. Moreover, this method was successfully applied to control the quality of Fuzi–Gancao herb couple.