Direct air capture (DAC) of CO2 is recognized to be a necessary complement to large point-source carbon capture due to the urgent need for a deep reduction in carbon emissions. As an energy-efficient regeneration mechanism, moisture-swing DAC (MSDAC) has received considerable attention in recent years. In this study, we extended the limited functional group types of MSDAC sorbent to most of the monovalent and divalent basic ions, and, for the first time, demonstrated experimentally the potential of cation-exchange-resins (CER) as MSDAC sorbents. Cation-exchange-resins loaded with various cations were tested, exhibiting an astounding CO2 capacity of 6.2 mmol/g in a chelating CER, significantly higher than the capacities of most MSDAC sorbents reported thus far. In addition, CERs can circumvent the common problem of hetero-ion contamination in MSDAC when using anion-exchange-resins (AER) as sorbents, thereby reducing the stringent need for high water quality, simplifying the MSDAC process and facilitating large-scale applications.