We predict the possibility of extending the lifetime and narrowing the linewidth of nuclear excited states through hyperfine interactions with bound electrons. For certain ionic charge states, the half-life of the ${}^{229}$Th isomeric state can be prolonged by 2%—16% compared with that of the bare nucleus. This effect originates from hyperfine branching and, more importantly, nuclear hyperfine mixing, which enables destructive interference between electronic and nuclear contributions to the transition matrix element, thereby suppressing specific decay channels. In ${}^{229}$Th, the lifetimes of individual decay channels can be extended by several to several tens of times relative to the no-mixing case. Calculations for ${}^{193}$Pt and ${}^{201}$Hg further demonstrate that this mechanism is not limited to low-energy isomers but also applies to nuclei with substantially higher excitation energies. Hyperfine-structured ions thus provide a versatile platform for controlling nuclear-state properties.