Autoclave treatment is an important processing step for the cooking and flavor development of packaged chestnut kernels. To compare the quality responses of different Yanshan chestnut cultivars to autoclave treatment, five cultivars, namely Zipo, Duanzhi, Dabanhong, Yanshan Zaofeng, and Dongling Mingzhu, were treated at 121 °C for 20 min. Changes in quality were characterized by color, texture, basic physicochemical properties, free amino acids, and quantitative descriptive sensory analysis. Volatile flavor profiles were further investigated using gas chromatography ion mobility spectrometry (GC-IMS), headspace solid phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS), and odor activity value (OAV) analysis. The results showed that autoclave treatment decreased the L value by 7.90% to 13.40%, hardness by 60.60% to 73.39%, and chewiness by 76.20% to 90.36%, while increasing the total free amino acid content by 34.90% to 41.10%. Roasted, caramel-like, and nutty aromas were enhanced, whereas grassy and floral-fruity aromas were weakened. A total of 51 and 84 volatile compounds were detected by GC-IMS and HS-SPME-GC-MS, respectively, of which 12 compounds were common to both analytical platforms. The compounds newly detected after treatment were mainly pyrazines, furans, and other heterocyclic compounds. OAV analysis indicated that 2-furanmethanethiol, 4,5-dihydro-3(2H)-thiophenone, and 2-ethyl-5-methylpyrazine could be considered candidate aroma-active compounds. Distinct cultivar-dependent quality responses were observed after autoclave treatment, providing a theoretical basis for raw material selection and quality regulation in the processing of packaged chestnut kernels.