Abstract: This study investigates how a processing technique designed to improve sensory quality affects flavor attributes and the relative concentrations of volatile and non-volatile compounds in Sichuan Gongfu black tea. The tea cultivar “Zhongcha 302” was used in the experiments. The impact of the processing technique on the aroma and taste qualities of Sichuan Gongfu black tea was evaluated by quantitative descriptive analysis, ultra-high-performance liquid chromatography–mass spectrometry (UPLC–MS/MS), and gas chromatography–mass spectrometry (GC–MS), combined with correlation analysis. The results showed that processing increased the sweet, floral, and fruity aromas, as well as the sweet and umami attributes of Sichuan Gongfu black tea. GC–MS analysis identified 34 key volatile compounds with odor activity values greater than 1, including geraniol, (E)-2-decenal, phenylacetaldehyde, nonanal, (E)-2-nonenal, o-cymene, (Z)-6-nonenal, (Z)-2-decenal, α-phellandrene, 2-pentylfuran, and heptanal. UPLC–MS/MS-based metabolomics identified 74 non-volatile compounds influenced by processing, including rutin, luteolin 7-xyloside, epicatechin gallate, p-coumaric acid, feruloyl-l-glutamic acid, and L-theanine. Tea processing altered the relative concentrations of several compounds, particularly flavonoids and phenolic acids (and their derivatives), as well as amino acids. Pearson correlation analysis showed that o-cymene, geraniol, phenylacetaldehyde, heptanal, p-cymene, trans-linalool oxide (furanoid), linalool, (E)-2-octenal, and α-ionone were associated with higher sensory scores for the floral, fruity, and sweet aroma attributes in the processed tea. The increased concentrations of L-glutamic acid, L-proline, and L-theanine were associated with greater umami and sweetness. In contrast, tea processing decreased the relative concentrations of luteolin 7-xyloside, epicatechin, p-coumaric acid, ferulic acid, theobromine, and proanthocyanidins, which may explain the reduced bitterness and astringency. These findings provide a theoretical basis and technical guidance for improving the quality of Gongfu black tea.