The development of materials for the efficient capture and delivery of toxic gases is crucial in both mitigating harmful emissions streams and enabling the safe storage and delivery of these gases for use in industry and medicine. Porous materials, specifically metal–organic frameworks (MOFs), represent a better alternative to molecular systems in attaining this goal through their structural tunability and precisely controlled gas–adsorbent interactions. Here, we describe efforts to design MOF-based systems for the irreversible capture of toxic chlorine (Cl2) gas and the reversible adsorption of hydrogen sulfide (H2S) gas for therapeutic delivery. We begin by reporting the first examples of irreversible Cl2 capture via the dichlorination of alkene linkages in zirconium-based MOFs. As a toxic and corrosive gas that is both an essential reagent in industry and a potent chemical warfare agent, Cl2 mitigation is needed for industrial and civilian personal protective equipment (PPE). MOFs constructed from alkene linkers were found to retain long-range order and accessible porosity after alkene dichlorination and could capture Cl2 at low partial pressures. Our results ultimately support that alkene dichlorination represents a new pathway for reactive Cl2 capture, introducing new opportunities for binding this gas irreversibly in PPE. We then proceed to review the emerging use of porous materials to deliver gases relevant to medicine, biomedical imaging, and pharmaceutical synthesis. Specific topics include MOFs and zeolites as solid-state sources of the gasotransmitter H2S, xenon-129 for magnetic resonance imaging, oxygen gas for the treatment of cancer and hypoxia, and various synthetically relevant gases prevalent in organic synthesis. We focus next on therapeutic H2S delivery in MOFs. H2S is an endogenous gasotransmitter with potential therapeutic value for treating a range of disorders, such as ischemia-reperfusion injury (IRI) resulting from a myocardial infarction or stroke. However, the medicinal delivery of H2S is hindered by its corrosive and toxic nature. In addition, small-molecule H2S donors often generate other reactive species upon H2S release, leading to unwanted side effects. We demonstrate that H2S release from biocompatible MOFs is a promising alternative strategy for H2S delivery under physiologically relevant conditions. These zirconium-based MOFs retain crystallinity and porosity after H2S adsorption and can deliver the gas to mitigate IRI-related injuries in rat cardiomyoblast cells using an in vitro model. Finally, we expand beyond zirconium-based MOFs and consider other framework materials that can bind H2S more strongly for transdermal delivery through porcine skin as a treatment of skin pathologies and wound healing. These studies intend to highlight the advantages of a MOF-based approach to harnessing toxic gases and demonstrate the potential for further adoption of these systems into the industrial and medicinal communities.